could you try latest -git (head v2.6.26-rc1-110-ga153063 or later).
There's scheduler interactivity fixes in it: in particular the
fair-sleepers latency bug was finally tracked down and fixed via
v2.6.26-rc1-66-ga992241 ("sched: fix normalized sleeper").
In v2.6.25 we didnt find that bug in time - see v2.6.25-rc9-1-ge2df9e0
('revert "sched: fix fair sleepers"').
Ingo
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