(Also see http://www.sharepointassist.com/2009/12/02/owstimer-pegging-cpu-and-filling-logs/)

Problem

SharePoint not responding or responding slowly and you note OWSTIMER.EXE and w3wp.exe running at a combined 100%? In my case this occurred because a developer created a workflow and executed it simultaneously on an entire list of at least a thousand items. What ends up happing is that you get a snowball effect of users and OWSTIMER trying to access the system, eventually it gets overwhelmed and the server stops serving pages.

Solution/Resolution

Disposition	Action
I need it up now	Stop OWSTIMER.EXE (not recommended)
I just need to make it until quitting time	Run IISReset every time the server stops serving user requests
I have all the time in the world	Just wait, the jobs will complete eventually
Long Term Solution	Buy more servers for job, search, and/or indexing

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