You may also check the memory utilization change over time as it could be that the server has memory leakage problems much like the browser of a similar name. If thats the case, an upgrade may address it.

That is of course if this has anything at all to do with the problem in the first place, but a running tally of memory use over time will point this out or clear it from consideration quickly.

Also if its memory related, once you determine the amount of ram gulped to make it slow you could restart based on that.