Imagine accounting for the time spent waiting for SharePoint to start up in the morning or after a server reboot or an iisreset?
It takes such a long time to load, but after it has loaded, then SharePoint behaves normally. The cause for this is when your Application pool is recycled in IIS. By default it recycles at 2:00AM daily.
The best way to ‘Warm Up’ SharePoint is to run some scripts that would fire up SharePoint in the wee hours of the morning. Read more on how to get this script..