I like to keep some of my most commonly used applications open in different Spaces all the time. These include Coda, iTunes, Bridge, Mail, iCal, Aperture, Firefox, and so forth. However, I find that after my MP goes to sleep or has just been on for a while with these apps open, OSX will lag and I will notice a severe performance hit that was not present while I was actively using the computer. The MP will eventually "get up to speed" and things will be back to normal, so I'm wondering if this is just a caching problem, normal operation, or otherwise?