Feeds: Hoist loop-invariant calls out of get_the_category_rss()

[mukeshpanchal27]

Trac ticket: https://core.trac.wordpress.org/ticket/66126

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[Copilot]

🟢 Approval recommended

The focused optimization preserves output and handles empty and feed-specific branches correctly.

Pull request overview

Optimizes feed category generation by moving repeated, loop-invariant lookups outside the category loop.

Changes:

• Caches the Atom category scheme once.
• Caches the blog charset once for non-Atom/RDF feeds.
• Avoids unnecessary lookups when no categories exist.

File summaries

File	Description
src/wp-includes/feed.php	Hoists invariant feed formatting calls outside the category loop.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Balanced

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Props mukesh27, westonruter.

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[westonruter]

The esc_attr() needs to be put back where it was. It is very important for security that values be escaped at the point where they are output. This prevents opportunities for vulnerabilities to be introduced when the value is modified after the escaping has been done, even innocently by some future contribution.

[westonruter]

LGTM, however I don't think the performance improvement will be measureable.