<p>I'm wondering if updating statistics has helped you before and how did you know to update them?</p>

```
```
exec sp_updatestats
```
```
Yes, updating statistics can be very helpful if you find that your queries are not performing as well as they should.  This is evidenced by inspecting the query plan and noticing when, for example, table scans or index scans are being performed instead of index seeks.  All of this assumes that you have set up your indexes correctly.
There is also the
UPDATE STATISTICS
command, but I've personally never used that.