The System process on the server was using this CPU time and using Process Explorer I was able to track the usage to the tmxpflt.sys thread. This file was part of the TrendMicro OfficeScan product, so the CPU usage was an AV issue. I searched the Internet for antivirus exclusions for SharePoint 2007, but wasn't able to find any exclusion information for SharePoint 2007. This ment I had to do the troubleshooting myself.
After some more troubleshooting I found out that:
- The Windows SharePoint Services Timer service started a job every minute which caused the issue. When I stopped this service, the CPU didn't spike at all.
- The Windows SharePoint Services Administration service was running the job. When I stopped this service when the CPU was high, the usage immediately dropped.
- The Windows SharePoint Services Administration service was writing some logging in the file WSS_AdminService.log, which was located in the directory C:\Documents and Settings\Default User\Local Settings\Temp.
- The WSS_AdminService.log file was about 65MB. TrendMicro OfficeScan scanned the file before the Administration service was able to write in it. With 65MB, this took some time and processing power.
After deleting the log file, the CPU usage didn't spike at all, so I excluded the C:\Documents and Settings\Default User\Local Settings\Temp directory which solved all issues!
So one exclusion for your Antivirus software when using SharePoint 2007: C:\Documents and Settings\Default User\Local Settings\Temp