My Macbook appears to get slow after a period of inactivity and then get itself back to full speed after 20-30 minutes.
While I have some ideas I'm wondering if anybody else has seen such behaviour or can offer some tips on how to investigate it further.
I have 16GB of RAM and I tend to run a reasonable workload. I have VMWare Fusion with a Windows and an Ubuntu guest running as well as Eclipse and Chrome (and probably Mail and iTunes).
Once I'm done for a while I'll either shut the lid or just leave the machine on and open. What I notice is that when I come back to it it can be dreadfully slow. Eclipse or the Windows guest can sit there for a 10-30 minutes with a spinning icon or not doing much.
After 20-30 minutes everything seems to come to full speed.
My guess is that MacOS is paging out everything in memory and then being forced to page it back in. However, I don't know enough about MacOS to provide evidence for this - nor to look for another explanation.