I had similar problem, exactly as described by topic starter - i.e. some "freeze" for a moment (not a stuttering, just a stop and go), just as a loading is underway.
I tried everything without any success (power control settings, driver updates, etc.), in the end I remembered that I installed new printer just before problem has appeared.
Problem was solved by completely removing printer from system. Suspect printer driver had a problem.
Probably my solution will be helpful for someone.