I'm usually in a 64-bit Linux VM (in VMware Workstation) on a 4 core i5 Xeon from about 3 years ago. 5 GB RAM total, Oracle Java 7 with -Xmx800M for Eclipse. My workspace includes 50 projects, most of them are Eclipse plug-ins themselves.
In my experience, if Eclipse "stops the world", Java is collecting garbage. Java 6 and 7 have become much better at doing incremental collection more often (maybe parallel is the default now?) and the result is a more responsive UI. To me, Eclipse itself feels snappier over time (each release from 3.3 to 3.7 has felt better on similar hardware).
Another thing I've noticed is that Eclipse is significantly faster cleaning/building large workspaces on Linux compared to Windows on the same hardware. I assume this is a result of Linux's aggressive filesystem caching.
In my experience, if Eclipse "stops the world", Java is collecting garbage. Java 6 and 7 have become much better at doing incremental collection more often (maybe parallel is the default now?) and the result is a more responsive UI. To me, Eclipse itself feels snappier over time (each release from 3.3 to 3.7 has felt better on similar hardware).
Another thing I've noticed is that Eclipse is significantly faster cleaning/building large workspaces on Linux compared to Windows on the same hardware. I assume this is a result of Linux's aggressive filesystem caching.