diff --git a/Cargo.lock b/Cargo.lock
index 24affbbd..30cf1eed 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1278,7 +1278,7 @@ dependencies = [
  "ahash",
  "egui",
  "enum-map",
- "itertools",
+ "itertools 0.15.0",
  "log",
  "profiling",
 ]
@@ -1331,6 +1331,7 @@ dependencies = [
  "emath",
  "env_logger",
  "log",
+ "nohash-hasher",
  "performance_lines",
  "serde",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 660a9426..adbdb583 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -64,6 +64,7 @@ env_logger = { version = "0.11.8", default-features = false, features = [
 ] }
 image = { version = "0.25", default-features = false }
 log = "0.4"
+nohash-hasher = "0.2.0"
 serde = { version = "1", features = ["derive"] }
 wasm-bindgen-futures = "0.4"
 web-sys = "0.3.83"
diff --git a/egui_plot/Cargo.toml b/egui_plot/Cargo.toml
index 8c38a0e7..bcc1640f 100644
--- a/egui_plot/Cargo.toml
+++ b/egui_plot/Cargo.toml
@@ -39,6 +39,7 @@ egui = { workspace = true, default-features = false }
 emath = { workspace = true, default-features = false }
 
 ahash.workspace = true
+nohash-hasher.workspace = true
 
 #! ### Optional dependencies
 ## Enable this when generating docs.
diff --git a/egui_plot/src/item_id.rs b/egui_plot/src/item_id.rs
new file mode 100644
index 00000000..1d1a4962
--- /dev/null
+++ b/egui_plot/src/item_id.rs
@@ -0,0 +1,64 @@
+//! Identifiers for the items within a plot.
+
+use core::hash::Hash;
+use core::num::NonZeroU64;
+
+/// The seeds used when hashing an [`ItemId`] source.
+///
+/// Fixed so that the same source always produces the same [`ItemId`],
+/// which is what lets [`crate::PlotMemory`] be persisted between runs.
+const HASH_SEEDS: (u64, u64, u64, u64) = (9, 10, 11, 12);
+
+/// An `ItemIdSet` is a `HashSet<ItemId>` that skips hashing,
+/// since an [`ItemId`] already is a high-entropy hash.
+pub type ItemIdSet = nohash_hasher::IntSet<ItemId>;
+
+/// An `ItemIdMap<V>` is a `HashMap<ItemId, V>` that skips hashing,
+/// since an [`ItemId`] already is a high-entropy hash.
+pub type ItemIdMap<V> = nohash_hasher::IntMap<ItemId, V>;
+
+/// Identifies a [`crate::PlotItem`] within a plot.
+///
+/// An `ItemId` only has to be unique within the plot it is used in.
+///
+/// By default each item derives its `ItemId` from the name it was created with,
+/// but you can set one explicitly, e.g. with [`crate::Line::id`]. Do that when
+/// the name changes between frames, or when several items share a name.
+///
+/// This is niche-optimized, so that `Option<ItemId>` is the same size as `ItemId`.
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct ItemId(NonZeroU64);
+
+impl nohash_hasher::IsEnabled for ItemId {}
+
+impl ItemId {
+    /// Hash any source (e.g. a string, an integer, or a tuple of those) into an [`ItemId`].
+    ///
+    /// Prefer a tuple over formatting a string:
+    ///
+    /// ```
+    /// # use egui_plot::ItemId;
+    /// # let (row, column) = (0, 0);
+    /// let good = ItemId::new(("my_cell", row, column)); // No allocation
+    /// let bad = ItemId::new(format!("my_cell {row} {column}")); // Allocates
+    /// # let _ = (good, bad);
+    /// ```
+    pub fn new(source: impl Hash) -> Self {
+        let (a, b, c, d) = HASH_SEEDS;
+        let hash = ahash::RandomState::with_seeds(a, b, c, d).hash_one(source);
+        Self(NonZeroU64::new(hash).unwrap_or(NonZeroU64::MIN)) // The hash was exactly zero (very bad luck)
+    }
+
+    /// The inner value, which is a high-entropy hash.
+    #[inline(always)]
+    pub fn value(self) -> u64 {
+        self.0.get()
+    }
+}
+
+impl core::fmt::Debug for ItemId {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "ItemId({:04X})", self.value() as u16)
+    }
+}
diff --git a/egui_plot/src/items/arrows.rs b/egui_plot/src/items/arrows.rs
index 75954404..685c054e 100644
--- a/egui_plot/src/items/arrows.rs
+++ b/egui_plot/src/items/arrows.rs
@@ -1,7 +1,7 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -10,6 +10,7 @@ use emath::Rot2;
 use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::data::PlotPoints;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -71,13 +72,15 @@ impl<'a> Arrows<'a> {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/bar_chart.rs b/egui_plot/src/items/bar_chart.rs
index 65415c22..a78caeea 100644
--- a/egui_plot/src/items/bar_chart.rs
+++ b/egui_plot/src/items/bar_chart.rs
@@ -1,8 +1,8 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
 use egui::CornerRadius;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -17,6 +17,7 @@ use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::colors::highlighted_color;
 use crate::cursor::Cursor;
+use crate::item_id::ItemId;
 use crate::items::ClosestElem;
 use crate::items::PlotConfig;
 use crate::items::PlotGeometry;
@@ -161,13 +162,15 @@ impl BarChart {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/box_plot.rs b/egui_plot/src/items/box_plot.rs
index c5de980d..5290f4fd 100644
--- a/egui_plot/src/items/box_plot.rs
+++ b/egui_plot/src/items/box_plot.rs
@@ -1,8 +1,8 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
 use egui::CornerRadius;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -16,6 +16,7 @@ use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::colors::highlighted_color;
 use crate::cursor::Cursor;
+use crate::item_id::ItemId;
 use crate::items::ClosestElem;
 use crate::items::PlotConfig;
 use crate::items::PlotGeometry;
@@ -127,13 +128,15 @@ impl BoxPlot {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/filled_area.rs b/egui_plot/src/items/filled_area.rs
index c4ec2593..06e11181 100644
--- a/egui_plot/src/items/filled_area.rs
+++ b/egui_plot/src/items/filled_area.rs
@@ -1,8 +1,8 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 use std::sync::Arc;
 
 use egui::Color32;
-use egui::Id;
 use egui::Mesh;
 use egui::Pos2;
 use egui::Shape;
@@ -14,6 +14,7 @@ use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::colors::DEFAULT_FILL_ALPHA;
 use crate::data::PlotPoints;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -115,10 +116,12 @@ impl FilledArea {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
+    ///
+    /// The id only has to be unique within the plot.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/line.rs b/egui_plot/src/items/line.rs
index cffb8609..042e39ca 100644
--- a/egui_plot/src/items/line.rs
+++ b/egui_plot/src/items/line.rs
@@ -1,7 +1,7 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -13,6 +13,7 @@ use crate::aesthetics::LineStyle;
 use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -97,13 +98,15 @@ impl HLine {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
@@ -232,13 +235,15 @@ impl VLine {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
+    ///
+    /// The id only has to be unique within the plot.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/mod.rs b/egui_plot/src/items/mod.rs
index 95d381bb..e88040de 100644
--- a/egui_plot/src/items/mod.rs
+++ b/egui_plot/src/items/mod.rs
@@ -8,7 +8,6 @@ use std::ops::RangeInclusive;
 
 use egui::Align2;
 use egui::Color32;
-use egui::Id;
 use egui::PopupAnchor;
 use egui::Pos2;
 use egui::Shape;
@@ -22,6 +21,7 @@ use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::cursor::Cursor;
+use crate::item_id::ItemId;
 pub use crate::items::arrows::Arrows;
 pub use crate::items::bar_chart::Bar;
 pub use crate::items::bar_chart::BarChart;
@@ -61,7 +61,7 @@ mod text;
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct PlotItemBase {
     name: String,
-    id: Id,
+    id: ItemId,
     highlight: bool,
     allow_hover: bool,
 }
@@ -69,7 +69,7 @@ pub struct PlotItemBase {
 impl PlotItemBase {
     /// Create a new plot item base with the given name.
     pub fn new(name: String) -> Self {
-        let id = Id::new(&name);
+        let id = ItemId::new(&name);
         Self {
             name,
             id,
@@ -141,8 +141,10 @@ pub trait PlotItem {
     /// Returns a mutable reference to the base data of the plot item.
     fn base_mut(&mut self) -> &mut PlotItemBase;
 
-    /// Returns the ID of the plot item.
-    fn id(&self) -> Id {
+    /// Returns the [`ItemId`] of the plot item.
+    ///
+    /// This only identifies the item within its plot.
+    fn id(&self) -> ItemId {
         self.base().id
     }
 
diff --git a/egui_plot/src/items/plot_image.rs b/egui_plot/src/items/plot_image.rs
index 1dc7a9b6..6c07a57c 100644
--- a/egui_plot/src/items/plot_image.rs
+++ b/egui_plot/src/items/plot_image.rs
@@ -1,8 +1,8 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
 use egui::CornerRadius;
-use egui::Id;
 use egui::ImageOptions;
 use egui::Shape;
 use egui::Stroke;
@@ -16,6 +16,7 @@ use emath::pos2;
 use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -114,13 +115,15 @@ impl PlotImage {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/points.rs b/egui_plot/src/items/points.rs
index faa523ac..62e88968 100644
--- a/egui_plot/src/items/points.rs
+++ b/egui_plot/src/items/points.rs
@@ -1,7 +1,7 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -15,6 +15,7 @@ use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::data::PlotPoints;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -100,13 +101,15 @@ impl<'a> Points<'a> {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/polygon.rs b/egui_plot/src/items/polygon.rs
index 84164c78..7fe1f88a 100644
--- a/egui_plot/src/items/polygon.rs
+++ b/egui_plot/src/items/polygon.rs
@@ -1,7 +1,7 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::Ui;
@@ -12,6 +12,7 @@ use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::colors::DEFAULT_FILL_ALPHA;
 use crate::data::PlotPoints;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -96,13 +97,15 @@ impl<'a> Polygon<'a> {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/series.rs b/egui_plot/src/items/series.rs
index f77ce8ba..0335b734 100644
--- a/egui_plot/src/items/series.rs
+++ b/egui_plot/src/items/series.rs
@@ -1,8 +1,8 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 use std::sync::Arc;
 
 use egui::Color32;
-use egui::Id;
 use egui::Mesh;
 use egui::Rgba;
 use egui::Shape;
@@ -21,6 +21,7 @@ use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
 use crate::colors::DEFAULT_FILL_ALPHA;
 use crate::data::PlotPoints;
+use crate::item_id::ItemId;
 use crate::items::ClosestElem;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
@@ -147,13 +148,15 @@ impl<'a> Line<'a> {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/items/text.rs b/egui_plot/src/items/text.rs
index c506104a..b4d626de 100644
--- a/egui_plot/src/items/text.rs
+++ b/egui_plot/src/items/text.rs
@@ -1,7 +1,7 @@
+use core::hash::Hash;
 use std::ops::RangeInclusive;
 
 use egui::Color32;
-use egui::Id;
 use egui::Shape;
 use egui::Stroke;
 use egui::TextStyle;
@@ -13,6 +13,7 @@ use emath::Align2;
 use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
 use crate::bounds::PlotPoint;
+use crate::item_id::ItemId;
 use crate::items::PlotGeometry;
 use crate::items::PlotItem;
 use crate::items::PlotItemBase;
@@ -74,13 +75,15 @@ impl Text {
         self
     }
 
-    /// Sets the id of this plot item.
+    /// Sets the [`ItemId`] of this plot item.
     ///
-    /// By default the id is determined from the name passed to [`Self::new`],
+    /// The id only has to be unique within the plot.
+    ///
+    /// By default the id is derived from the name passed to [`Self::new`],
     /// but it can be explicitly set to a different value.
     #[inline]
-    pub fn id(mut self, id: impl Into<Id>) -> Self {
-        self.base_mut().id = id.into();
+    pub fn id(mut self, id: impl Hash) -> Self {
+        self.base_mut().id = ItemId::new(id);
         self
     }
 }
diff --git a/egui_plot/src/lib.rs b/egui_plot/src/lib.rs
index ac7c4033..608cf584 100644
--- a/egui_plot/src/lib.rs
+++ b/egui_plot/src/lib.rs
@@ -15,6 +15,7 @@ mod colors;
 mod cursor;
 mod data;
 mod grid;
+mod item_id;
 mod items;
 mod label;
 mod math;
@@ -40,6 +41,9 @@ pub use crate::grid::GridInput;
 pub use crate::grid::GridMark;
 pub use crate::grid::log_grid_spacer;
 pub use crate::grid::uniform_grid_spacer;
+pub use crate::item_id::ItemId;
+pub use crate::item_id::ItemIdMap;
+pub use crate::item_id::ItemIdSet;
 pub use crate::items::Arrows;
 pub use crate::items::Bar;
 pub use crate::items::BarChart;
diff --git a/egui_plot/src/memory.rs b/egui_plot/src/memory.rs
index b0b0aa0e..f47003d0 100644
--- a/egui_plot/src/memory.rs
+++ b/egui_plot/src/memory.rs
@@ -7,6 +7,8 @@ use egui::Vec2b;
 
 use crate::axis::PlotTransform;
 use crate::bounds::PlotBounds;
+use crate::item_id::ItemId;
+use crate::item_id::ItemIdSet;
 
 /// Information about the plot that has to persist between frames.
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -19,10 +21,10 @@ pub struct PlotMemory {
     pub auto_bounds: Vec2b,
 
     /// Hovered legend item if any.
-    pub hovered_legend_item: Option<Id>,
+    pub hovered_legend_item: Option<ItemId>,
 
     /// Which items _not_ to show?
-    pub hidden_items: ahash::HashSet<Id>,
+    pub hidden_items: ItemIdSet,
 
     /// The transform from last frame.
     pub(crate) transform: PlotTransform,
diff --git a/egui_plot/src/overlays/legend.rs b/egui_plot/src/overlays/legend.rs
index f0da5975..3396e295 100644
--- a/egui_plot/src/overlays/legend.rs
+++ b/egui_plot/src/overlays/legend.rs
@@ -4,7 +4,6 @@ use egui::Align;
 use egui::Color32;
 use egui::Direction;
 use egui::Frame;
-use egui::Id;
 use egui::Layout;
 use egui::PointerButton;
 use egui::Rect;
@@ -21,6 +20,9 @@ use egui::epaint::CircleShape;
 use egui::pos2;
 use egui::vec2;
 
+use crate::item_id::ItemId;
+use crate::item_id::ItemIdMap;
+use crate::item_id::ItemIdSet;
 use crate::items::PlotItem;
 use crate::placement::Corner;
 
@@ -41,7 +43,7 @@ pub enum LegendGrouping {
     #[default]
     ByName,
 
-    /// Each item gets its own legend entry, keyed by its unique [`Id`].
+    /// Each item gets its own legend entry, keyed by its [`ItemId`].
     ById,
 }
 
@@ -59,7 +61,7 @@ pub struct Legend {
     color_conflict_handling: ColorConflictHandling,
 
     /// Used for overriding the `hidden_items` set in [`LegendWidget`].
-    hidden_items: Option<ahash::HashSet<Id>>,
+    hidden_items: Option<ItemIdSet>,
 }
 
 impl Default for Legend {
@@ -112,7 +114,7 @@ impl Legend {
     #[inline]
     pub fn hidden_items<I>(mut self, hidden_items: I) -> Self
     where
-        I: IntoIterator<Item = Id>,
+        I: IntoIterator<Item = ItemId>,
     {
         self.hidden_items = Some(hidden_items.into_iter().collect());
         self
@@ -139,7 +141,7 @@ impl Legend {
     ///
     /// With [`LegendGrouping::ByName`], items sharing the same name are
     /// merged into a single legend entry. With [`LegendGrouping::ById`],
-    /// each item gets its own entry keyed by its unique [`Id`].
+    /// each item gets its own entry keyed by its [`ItemId`].
     #[inline]
     pub fn grouping(mut self, grouping: LegendGrouping) -> Self {
         self.grouping = grouping;
@@ -149,7 +151,7 @@ impl Legend {
 
 #[derive(Clone)]
 struct LegendEntry {
-    id: Id,
+    id: ItemId,
     name: String,
     color: Color32,
     checked: bool,
@@ -157,7 +159,7 @@ struct LegendEntry {
 }
 
 impl LegendEntry {
-    fn new(id: Id, name: String, color: Color32, checked: bool) -> Self {
+    fn new(id: ItemId, name: String, color: Color32, checked: bool) -> Self {
         Self {
             id,
             name,
@@ -247,21 +249,21 @@ impl LegendWidget {
         rect: Rect,
         config: Legend,
         items: &[Box<dyn PlotItem + 'a>],
-        hidden_items: &ahash::HashSet<Id>, // Existing hidden items in the plot memory.
+        hidden_items: &ItemIdSet, // Existing hidden items in the plot memory.
     ) -> Option<Self> {
         // If `config.hidden_items` is not `None`, it is used.
         let hidden_items = config.hidden_items.as_ref().unwrap_or(hidden_items);
 
         // Collect the legend entries. With `ByName` grouping, items sharing the
         // same name are merged into a single checkbox. With `ById` grouping,
-        // items sharing the same `Id` are merged instead. When colors conflict
+        // items sharing the same `ItemId` are merged instead. When colors conflict
         // within a merged entry, `color_conflict_handling` decides which color
         // to show.
         let mut entries: Vec<LegendEntry> = Vec::new();
-        let mut seen: ahash::HashMap<Id, usize> = ahash::HashMap::default();
+        let mut seen: ItemIdMap<usize> = ItemIdMap::default();
         for item in items.iter().filter(|item| !item.name().is_empty()) {
             let dedup_key = match config.grouping {
-                LegendGrouping::ByName => Id::new(item.name()),
+                LegendGrouping::ByName => ItemId::new(item.name()),
                 LegendGrouping::ById => item.id(),
             };
 
@@ -292,7 +294,7 @@ impl LegendWidget {
     }
 
     // Get the names of the hidden items.
-    pub fn hidden_items(&self) -> ahash::HashSet<Id> {
+    pub fn hidden_items(&self) -> ItemIdSet {
         self.entries
             .iter()
             .filter_map(|entry| (!entry.checked).then_some(entry.id))
@@ -300,7 +302,7 @@ impl LegendWidget {
     }
 
     // Get the name of the hovered items.
-    pub fn hovered_item(&self) -> Option<Id> {
+    pub fn hovered_item(&self) -> Option<ItemId> {
         self.entries.iter().find_map(|entry| entry.hovered.then_some(entry.id))
     }
 }
@@ -388,7 +390,7 @@ fn handle_interaction_on_legend_item(response: &Response, entry: &mut LegendEntr
 }
 
 /// Handle alt-click interaction (which may affect all entries).
-fn handle_focus_on_legend_item(clicked_entry: &Id, entries: &mut [LegendEntry]) {
+fn handle_focus_on_legend_item(clicked_entry: &ItemId, entries: &mut [LegendEntry]) {
     // if all other items are already hidden, we show everything
     let is_focus_item_only_visible = entries
         .iter()
diff --git a/egui_plot/src/plot.rs b/egui_plot/src/plot.rs
index b7687e32..b4cb76b1 100644
--- a/egui_plot/src/plot.rs
+++ b/egui_plot/src/plot.rs
@@ -42,6 +42,7 @@ use crate::cursor::PlotFrameCursors;
 use crate::grid::GridInput;
 use crate::grid::GridMark;
 use crate::grid::GridSpacer;
+use crate::item_id::ItemId;
 use crate::items;
 use crate::items::PlotItem;
 use crate::items::Span;
@@ -977,7 +978,7 @@ impl<'a> Plot<'a> {
         legend: Option<LegendWidget>,
         ui: &mut Ui,
         mem: &mut PlotMemory,
-        hovered_plot_item: &mut Option<Id>,
+        hovered_plot_item: &mut Option<ItemId>,
     ) {
         if let Some(mut legend) = legend {
             ui.add(&mut legend);
@@ -1323,7 +1324,7 @@ impl<'a> Plot<'a> {
         plot_id: Id,
         transform: &PlotTransform,
         show_xy: Vec2b,
-    ) -> (Vec<Shape>, Vec<Cursor>, Option<Id>) {
+    ) -> (Vec<Shape>, Vec<Cursor>, Option<ItemId>) {
         let mut child_ui = ui.new_child(
             egui::UiBuilder::new()
                 .max_rect(*transform.frame())
@@ -1555,7 +1556,7 @@ impl<'a> Plot<'a> {
         plot_ui: &PlotUi<'_>,
         transform: &PlotTransform,
         show_xy: Vec2b,
-    ) -> (Vec<Cursor>, Option<Id>) {
+    ) -> (Vec<Cursor>, Option<ItemId>) {
         if !show_xy.any() {
             return (Vec::new(), None);
         }
@@ -1877,7 +1878,7 @@ pub struct PlotResponse<R> {
     /// This is `None` if either no item was hovered.
     /// A plot item can be hovered either by hovering its representation in the
     /// plot (line, marker, etc.) or by hovering the item in the legend.
-    pub hovered_plot_item: Option<Id>,
+    pub hovered_plot_item: Option<ItemId>,
 }
 
 /// Provides methods to interact with a plot while building it. It is the single
diff --git a/examples/interaction/src/app.rs b/examples/interaction/src/app.rs
index 47927143..bd3cc151 100644
--- a/examples/interaction/src/app.rs
+++ b/examples/interaction/src/app.rs
@@ -1,5 +1,6 @@
 use eframe::egui;
 use eframe::egui::Response;
+use egui_plot::ItemId;
 use egui_plot::Line;
 use egui_plot::Plot;
 use egui_plot::PlotPoint;
@@ -13,7 +14,7 @@ pub struct InteractionExample {
     last_pointer_coordinate: Option<PlotPoint>,
     last_pointer_drag_delta: egui::Vec2,
     last_hovered: bool,
-    last_hovered_item: Option<egui::Id>,
+    last_hovered_item: Option<ItemId>,
 }
 
 impl InteractionExample {
@@ -83,9 +84,9 @@ impl InteractionExample {
         );
         ui.label(format!("pointer coordinate drag delta: {coordinate_text}"));
 
-        let hovered_item = if self.last_hovered_item == Some(egui::Id::new("sin")) {
+        let hovered_item = if self.last_hovered_item == Some(ItemId::new("sin")) {
             "red sin"
-        } else if self.last_hovered_item == Some(egui::Id::new("cos")) {
+        } else if self.last_hovered_item == Some(ItemId::new("cos")) {
             "blue cos"
         } else {
             "none"
diff --git a/examples/markers/src/app.rs b/examples/markers/src/app.rs
index 975acd95..16a10a5d 100644
--- a/examples/markers/src/app.rs
+++ b/examples/markers/src/app.rs
@@ -40,7 +40,7 @@ impl MarkerDemo {
                         [6.0, 0.5 + y_offset],
                     ],
                 )
-                .id(format!("marker_{i}"))
+                .id(("marker", i))
                 .name(format!("{marker:?}"))
                 .filled(self.fill_markers)
                 .radius(self.marker_radius)