Library help?

[Aeriez]

Im not new to UIs. Been using them since release for most part. However ive never made them and never really tried. I downloaded a UI package a while ago and noticed that it increased my load times and such by at least 10x. Going though all the add ons (deleting ones i know ill never use) i noticed that almost half of the addon folders were libraries. How do i determine which libraries arent needed or wont be used so WoW isnt loading them up sucking up a ton of system resources?