How long does IIS retain compiled ASP.NET in cache before needing to be recompiled?

I am testing a piece of software called PowershellASP which lets you run powershell scripts inside an ASP.NET page, which I am driving via IIS 7.

Basically, on my test page, the first time it loads it takes over 60 seconds, which I assume is because the ASP.net needs to compile? It is fast on subsequent loads, except it then goes back to requiring 60 seconds+ if I leave it for an hour or so and then try refreshing the page after an hour... Any insight on the likely culprit for this behaviour (i.e. its "slow" after I try to refresh the page after an hour or so)...

Is this the IIS cache expiring and thus needing to recompile the ASP.NET page I'm trying to load or am I barking up the wrong tree?

regards, ted.

EDITED:To increase the idle timeout of a iis application go to advanced settings of your application pool and change the idle timeout to 0. Default is 20 min. The IIS doesn't exactly compile your application it load it into a worker which can take some time based on your application and the iis settings. After some idle the iis automaticly unload your application to save resources, that is why it takes more time after a while. Ones the app is loaded it runs fast.