I have a SQL server with about 150 tables and the 5 tables that are used the most consist of over 10 million rows each. I'm trying to see why the performance of the server has been diminishing day by day.

This is a corporate SQL server and we have never had a DBA to help with the server and it has gotten to the point where pulling 1000 records from one table can take 20 min.

The cpu is not pegging above 50% nor is the ram going above 2 gig of usage.

The I/O reads however are at 1.9 trillion reads in the last 48hrs.

I need some direction on how to attack this issue.

I heard something about having rowguid's causing issues with tables with millions of rows is this accurate?