I had exactly the same problem. And finally I've found a workaround.

In my case, I also use sshfs, and I've been looking at the unix "top" application to see which process was eating my computer, until I realised that the problem was caused in the combination of sshfs mounted filesystem and textmate (most times, meanwhile I was looking for something in a big project with textmate).

The process that was eating all cpu was mdworker / mds (spotlight daemon)

So I tried to disable spotlight completely and the problem didnt happen again. When I turned on spotlight... I was able to work for a whlie... and then the beachball appeared again, so what I've done is to add the folder where I mount the sshfs filesystem to Privacy Tab, to prevent Spotlight from indexing the content of the sshfs mounted filesystem.

And no more issues.  In my case I'm using virtualbox with a headless ubuntu server 8.04

Hope this helps

Miquel