Severe SQL Server 2005 database performance issues

DenSter wrote:

It is quite common to have performance issues with NAV on SQL Server. This is such a complicated area though that each implementation has its own set of unique problems.

In general:

• Make sure your hardware is up to standards. At the very least it is recommended to separate storage of the data files from the operating system spindles, with a dedicated physical drive for the transaction log. Do NOT use RAID 5, no matter what your hardware vendor tells you.
• Put in place maintenance plans for your SQL Server database. Unlike the native C/SIDE database server, which can be installed and forgotten, SQL Server needs to be maintained. There are many posts about this, so you might want to search the forum. You can purchase tools for this, and personally I have my preference about which tools to use
• Your tables will probably need to be tuned. The tools I just spoke about also has analysis capabilities to help quickly identify which tables to tune. You can also analyze the system manually, but that will take much more time.
• Code review. This you should not do until you have done all other steps, as it gives the least 'bang for the buck'

Of course these are general guidelines. Your situation might be completely different. If the code is bad enough, it will be a much bigger problem than usual. Hardware upgrades, as long as the initial hardware was set up properly, usually doesn't provide nearly as much improvement as expected. I have to say though that I have also seen hardware upgrades make a HUGE difference, even though at first I was not sure if that would make much of a difference.

You would probably benefit from having an experienced specialist involved to help you. Start with your partner, and if they don't have the right resources I'd recomend getting someone externally involved.