title: ASP.Net application getting slow over time
body: <p>Our users of a legacy web application written in ASP.net 2.0 are experiencing slow down after using the application over some time (after 2 hours or so).
  For example, clicking a button performing some calculation and updating an ajax updatepanel takes several seconds while it is almost instant when they just have logged in.</p>
  
  <p>If they log off and log back on of the web application, it gets back to the normal speed again, every time they do. The slow down is for a particular user and not global. It can fast for an user and slow for the user next to him.</p>
  
  <p>I've looked at the IIS server and there is plenty of free memory in it and the CPU is almost always below 10%.
  There are only a dozen users using this web application at time so scalability shouldn't be an issue.</p>
  
  <p>The only think I can think of being affected by log offs, is session state.
  I've already looked ViewState too and it is "only" 18kb at the slowest which shouldn't be the bottleneck, especially since they are on the same gigabit LAN and not remote. It is not any smaller when the applications runs fast.
  Looking at session state in the code, it isn't used much and no large objects are stored.
  According to my tests, it didn't grow bigger than 10 items and 500 bytes after a few minutes.
  Even if there was a leak, the server should be able to cope with it considering the amounts of memory it has (4GB but only using 300MB).</p>
  
  <p>I've cleared temporary files and it didn't seem to make any significant difference.</p>
  
  <p>Do you think these slowdowns could come from something else than Session State, keeping in mind logging off and back on gets the speed back to normal?
  If not, is there any tool you would suggest to profile sessionstate or a setting in IIS I should try to change?</p>