I think more usefull is simple knowledge of major rewrites couse they're mainly changing the speed. Maybe you find those usefull:
- For example already mentioned texture cache which fixed loads of game and completely destroyed the speed of a few(like described here
which was implemented around 4600(through not included in that one).
- Gif transfer rewrite which "happened" at r4821
it decreased cpu load/speeded up a bit quite a few of games for me and seem to not cause any issues meaning it's worth checking.
- For any VU/EE heavy game or generally a multi core cpu users r4865
brings on MTvu speedhack which everyone loves;P.
- Latest GSdx versions also change alot of stuff giving different results like you see with VP2, they also fix quite a bit of stuff, but it's mainly software mode.
Most other stuff unless I forgot any other important change affecting speed, is pretty much oriented over small fixes and is worth checking only if you experience some bugs in your game, you can easily search through repository with google:
site:http://code.google.com/p/pcsx2/source/list "game name here"
For just playing, ie not interested soo much over testing new bugs(I mean features;P), I don't see much point of hunting for best pcsx2 version for each game. It's damn hard to notice small fps increase/decrease in pcsx2 anyway, as even with frame limiter on and playing on full speed it jumps around by 2-3 fps constantly.
Oh and I didn't found your post offending;P, just didn't want my own to be taken like that either. Actually if you're testing and see your game slowed down radically or got bugged, make sure to find exactly which revision slowed it down. Posting that info at google code have biggest chance for eventual in-deepth explanation or even a fix, through by general rule which applies most of the time, speed drop in svn versions of pcsx2 is not considered a bug.