SQL Server becomes slow after restart

We use SQL Server 2005 on an Windwos Server 2008. Ther Server has 48 GB RAM. SQL Server is configured to use 40 GB RAM. There is only one database hosted (About 70 GB). The only app beside SQL Server is our App-Server which connects the clients to the database.

Now we encounter the following problem:

After a restart of开发者_JS百科 the server our the performance is great. The server grabs the 40 GB RAM wich it is allowed to and then runs fast as hell. But after about 4 weeks the system becomes slower and slower. The execution of statements (seen in the profiler) is raising slowly. But I cannot see that there is something going wrong on the server.

• CPU usage is at about 20%
• I/O also seems to be no Problem
• The process monitor does also not show that there are strange apps or something like that.
• Eventlog does also have no interessting messages
• No open transactions or blockings to see

We tried already the following things without effect:

1. Droped the cache by using the statements

   DBCC FreeProcCache
   DBCC FREESYSTEMCACHE('ALL')
   DBCC DropCleanbuffers
   

2. Restarted the Appserver we are using.

3. Restart the sql server service

But nothing did help exept restarting the whole server. Any ideas?

Sounds like you may have a memory leak somewhere. Do you by any chance use cursors somewhere in your app? It may be that you're not properly closing and releasing the resources on these, but then a restart of the SQL Server service should sort out this problem.

Could it be a connection leak? If the number of active conections reaches extremely high numbers, it will cause poor performance. Check out this page: Diagnosing SqlConnection leaks?

This is an old question but.... sounds like a corrupt TempDB / TempB optimization problem.