I quote
https://forum.kerbalspaceprogram.com/index.php?/topic/50533-140-16x-module-manager-402-february-3rd-2019-right-to-ludicrous-speed/&page=251&tab=comments#comment-3539665
File https://github.com/KSP-RO/RealSolarSystem/blob/v14.0.0/GameData/RealSolarSystem/RSSKopernicus/Earth/Earth.cfg has the line "cbNameLater = Earth" that needs to be killed. "Template {name=Kerbin}" is ok and so is "Properties {displayName = Earth}". cbRenameLater has been deprecated and now all the more recent mods use Kerbin as the primary's name in their internal config. @galileo did it for GPP a few months back. I had to go through a history of "Couldn't find CelestialBodyName Kerbin" log errors and also Gael errors in order to understand the stuttering problem. Had to go through the forum history for every mention of that error. It took me a week to figure it out.
I quote
https://forum.kerbalspaceprogram.com/index.php?/topic/50533-140-16x-module-manager-402-february-3rd-2019-right-to-ludicrous-speed/&page=251&tab=comments#comment-3539665