There's one I used for this that did seem to work, sorta. I can't remember which one it was, though. Here are a few options I found online.

http://eve.grismar.net/evelauncher/
http://gwr.orekaria.com/
There is also one called StartEVE but I couldn't find a link to that one.
EVEMon also does something like this but I'm not sure it will tile windows like you want.

Also, none of these will "reduce framerates" on background windows as far as I know. I thought that was a WoW engine feature, not a multiboxing software feature.

[edit] http://www.eve-search.com/thread/1110391-0/page/1