Also, I'd like to be able to disable all the unneeded stuff (unneeded plugins, unneeded exports to win8, linux, kongregate, tyson, firefox, Arcade, bb, etc) to see if that helps keep C2 lean and clean.
Did a particular release make it slower or has it been gradual?
If it's gradual it's likely just the increasing executable size. Windows 7 should be a bit faster than Windows XP since it caches regularly used applications. If you have a very large number of third party plugins, removing them should help speed it up too (since it has to run every plugin's edittime script on startup). Disabling or removing anything else will probably have no effect at all.