[Periodic Freezing]

Sorry I forgot to get back to you sooner, but everything is better now, thanks!

[Periodic Freezing]

I just installed the update, I'll let you know how it goes.  Great to see this!

[Periodic Freezing]

I don't have time right now to do the experiments people are talking about, but I wanted to throw out a possible clue.

I've just started getting this hitching this morning, and started wondering what might have changed to cause it.  For what it's worth, yesterday I rebooted the computer after a 2-3 weeks, and it installed a Microsoft update.  This morning, I opened Chrome (with about 25 tabs open) for the first time since the update.  Chrome definitely seems to be a big problem here, although all those tabs were open before the update.  Not sure if that helps.