title: Stored procedure performance inconsistancy
body: <p>We're experiencing a strange scenario when running stored procedures on SQL Server. When running the exact same procedure with the same parameters (we've captured this via SQL Server Profiler) we get very variable CPU usage. Now obviously this depends on the server load and other activities that are going on on the server. However, I'd not expect the variability in "reads" that we are experiencing when running the SP on subsequent occasions - only a few minutes apart.</p>
  
  <pre><code>Day  Hour Min CPU      Reads
  70  15  54  4851    33079
  70  15  54  5960    33723
  70  15  58  5538    30189
  70  16  10  5226    29672
  70  16  12  24102   1019178
  70  16  17  23915   1017621
  70  16  17  26348   1018690
  70  16  30  6443    28121
  70  16  30  6474    28539
  70  16  33  5242    27245
  70  16  33  6365    27338
  70  16  35  5413    27335
  </code></pre>
  
  <p>Bizzare. Why would we suddenly get a load of reads when we've previously not that then reset themselves. Again I'd say - we have the exact same parameters to this procedure so why it suddenly decides that it's got to do a load of reads is just a bit odd.</p>
  
  <p>Any thoughts on what to look at ? We know that there might be some benefit from some additional queries (Query analyser suggests one for instance) but we wouldn't we expect to see roughly the same number of reads ?</p>
  
  <p>Thanks
  Andy</p>