Does it really make sense for them to live in the heap rather than in the disk buffers?
I presume that you're not hitting a melt-down from CPU time, so I'd assume you'd get better performance by letting the system handle paging in data from the disk and figuring out which stuff needs to be in memory (buffers) and lives out on disk.
Also one thing to watch out for when you make the 64-bit jump is that (internally pointer-heavy) applications in dynamic languages tend to use significantly more memory on 64-bit platforms. davidw talked about this some here:
I presume that you're not hitting a melt-down from CPU time, so I'd assume you'd get better performance by letting the system handle paging in data from the disk and figuring out which stuff needs to be in memory (buffers) and lives out on disk.
Also one thing to watch out for when you make the 64-bit jump is that (internally pointer-heavy) applications in dynamic languages tend to use significantly more memory on 64-bit platforms. davidw talked about this some here:
http://journal.dedasys.com/2008/11/24/slicehost-vs-linode