I have a production SQL Server 2005 SP2 instance hosting over 150 databases. Every day or so the server performance slows considerably for all SQL services. Upon inspection I see a dozen or so threads of â€˜UPDATE STATISTICSâ€™ running with many in a wait state. If I kill the sessions(s) running the statistics the normal performance returns. I know that statistics play an important role in determining execution plans, but should I disable auto update statistics for all databases and run the update statistics manually during off-peak times? Will this prevent the update from running automatically? Is there a way to limit the number of threads the update statistics uses? Thanks for any advice on this subject.