100% CPU

I'm trouble shooting a site where the server CPU stays at 100% (w3wp.exe process housing DNN) for over an hour.  The site has 800+ pages and about 12,000 page views a day so this is really affecting a lot of people.

During the time the cpu is max'd I see that the files in \DesktopModules\Snapsis\PageBlaster\Cache\tabid  are not staying for much longer then a few minutes.  The folder stays but is emptied regularily.

To test it, I set the memory cache time in the config to 8 hours and disk to 4 days but this had no effect.

The trace files shows IsPageExcluded: Exception and Replacements Error every hour to half hour.   (sidebar, I also see it uses deflate occasionaly, perhaps 5% of the time - why is that?)

I would like to know if you have experienced this issue with Snapsis (plus the SEO Dynamic Keywords plugin). Would one of the modules be causing this short cache time?

If not, any guesses or clue as to how I find out what is cauing this?

It is possible that the cache is being cleared by an automatic post-back.  Do you have an Ajax type module on the page?  A photo gallery or content rotator perhaps?  If so, then I recommend exculding that page from caching.

I don't think it would cause 100% cpu for that long though.  Sometimes a run-away regular expression can cause that.  If you are doing replacements on the page, try disabling that to see if it makes the 100% cpu problem go away.  Also try it with the Dynamic Keywords module disabled to try and isolate it.

Deflate may be used even if you specify GZip if that is all the client browser says it can use.