Plugins such as Coolplayer, WP-Grins, WP-Polls and WP-Table load whether they are needed on the page or not.
My site is slow, and I believe this is a prime reason.
Why do they load when they aren't needed?
Can I edit them so they don't?
For example, see http://www.imagiscape.ca/blog/category/arts/poetryliterature and it's source.
Anarchy Media Player, if I'm not mistaken, also loaded on every page whether there was media to load or not. I disabled it.
CoComment also makes my blog slow.
(I deactivated the Show CoComment plugin and widget, but I once upon a time added some code from a CoComment.com integration/installation instructions. I'll use the grep command via PuTTY to search for the code, and remove it. From the blog directory: grep -r 'cocomment' * .)
ClickTracking also slowed my site - but reasonably. I hope to reactivate it when I've got other issues resolved.
AddThis sometimes slows things down, but it didn't the last time I checked.