Our SS 2000 database is usually satisfactorily responsive most of the time, but there are times during the day that the response time becomes unacceptible; ie queries that typically take 1 to 8 seconds take longer than 30 seconds.

The slowdowns seem to take place hourly for about 10 minutes (like from :30 to :40), then speed up again, some episodes worse than others.

Performance counters show that sqlservr is increasing CPU time dramatically during these periods, but I've been having difficulty pinpointing what exactly is taxing it, using profiler.

All of the jobs that are scheduled through those times are fairly simple and none of the job histories show durations of more than a minute (although all of them take longer during the slowdowns).

I'm wondering if housekeeping tasks are involved, such as auto updating statistics or indexes but I understand they don't work on a schedule but as needed.

Any pointers or suggestions would be greatly appreciated

Thanks,

Darren

 Can you review sql server log events,  review all information /warning within the period of that performance problem.

It may due to autogrow of database data /log files. 

profiler is still the best tool to discover that problems. 

Welcome to the forum.

SEe this http://sqlserver-qa.net/blogs/perftune/archive/2008/02/05/3182.aspx on how to startup on the performance tuning exercises.