I think that any eclipse users has experimented the fact that eclipse tends to slow down. In the past I had to reinstall the whole environment especially after loading new plugins that was probably breaking something down. Btw I always followed as best practice to clen up eclipse any 6 months and I learned fast how to export preferences to be able to push them into the new install. In this way to pass to a new and clean eclipse install is quite painless.
In the last period I tried to reduce the number of opened projects in my workspace to the really important ones, and I also experimented the solution of mantaining many workspaces but I do not feel very compofortable with that.
I then got the idea to check what kind of settings eclipse was passing to the jvm and blogging around I found a great post of Mike Henke.
I added the following arguments to my eclipse.ini file:
<code class="coldfusion">
-vm
C:Program FilesJavajre1.6.0_12injavaw.exe
-vmargs
-Xms512m
-Xmx512m
-XX:PermSize=128m
-XX:MaxPermSize=128m
-Xverify:none</code>
The vm path depends on what do you have available in your machine, but I suggest you to update at least to version 1.6 update 12. Be carefull do not leave extra white spaces and .... look your turbo eclipse start to fly...