I played around with the settings a lot. I have a k6-2 400 with only 80 megs of ram, so I was in need of the optimization. It actually helps quite a bit. I have these settings currently and they provide a pretty good mix of speed and stability.
Minimal Disk Cache: 14073kb
Maximal Disk Cache: 14073kb
Chunk Size: 512Bytes
Name Cache: 2004
Directory Cache: 24
It is recommended to set the minimal and maximal disk cache to the same value so that there is no time wasted by the OS trying to dynamically resize it. I can get better performance by setting the cache values higher (other than chunk size which seems to make no difference), but my system crashes more often.