Work Unit Runtimes and 5970

Hi folks.

I am currently experiencing some strange WU runtimes variations.

I have 2 identical machines and on one the WU were taking about 1:30 each whereas the second machine was taking 3:30. Now I upgraded the second machine to Catalyst 10.6 from 10.3 and am seeing its times drop to 1:30 ish. So I upgraded my 1st machine from 10.5 to 10.6 and its times have risen to 3:30. So I'm puzzled as to why both machines seem to vary and damn why the hell can I not get 2 running at 1:30.

No BOINC settings were changed during the making of this weird scenario.