The UI & Export "SkillsFilter" implemented in SVN 22104 (to support and ) thrashes the skills on the PC.
(meaning it takes a set of skills, adds them, clears the list, determines a new list, adds those, then in a few moments will repeat the cycle constantly adding and removing skills)
The SkillsFilter needs to be moved solely to an Export / UI function and not reside in the core.
In its initial implementation this was crippling to performance, see for the cleanup of that situation.
Closed as moot. Fixed in other changes to skills