title: SQL Server query performance slows over time
body: <p>I've seen this question asked in many ways all over the Internet but despite implementing the abundance of advice (and some voodoo), I'm still struggling.  I have a 100GB+ database that is constantly inserting and updating records in very large transactions (200+ statements per trans).  After a system restart, the performance is amazing (data is written to a large SATA III SSD connected via USB 3.0).  The SQL Server instance is running on a VM running under VMWare Workstation.  The host is set to hold the entire VM in memory.  The VM itself has a paging cache of 5000 MB.  The SQL Server user is set to 'hold pages in memory'.  I have 5 GBs of RAM allocated to the VM, and the max memory of the SQL Server instance is set to half a Gig.  </p>
  
  <p>I have played with every single one of these parameters to attempt to maintain consistent performance, but sure and steady, the performance eventually degrades to the point where it begins to time out.  Here's the kicker though, if I stop the application that's loading the database, and then execute the stored proc in the Management Studio, it runs like lightning, clearly indicating it's not an issue with the query, and probably nothing to do with memory management or paging.  If I then restart the loader app, it still crawls.  If I reboot the VM however, the app once again runs like lightning...for a while...</p>
  
  <p>Does anybody have any other suggestions based upon the symptoms presented?</p>