Eclipse using lots of memory, freezing and slow?

I downloaded Version: Helios Service Release 2 -Build id: 20110218-0911, no plugins JEE version of Eclipse and starts up using 512 MB in heap out of 768, I click on trashcan to GC and it goes down to 64MB - then I try to copy and paste one work in java editor and memory jumps up to 500mb and freezes for 5min - every time. Any way to turn something off or fix this - right now all default settings with jdk 1.6.0.17 on widnows xp (4gb ram dual core 3ghz amd)