So, I went to play a game of vanilla Sins recently and in just a 3v3 the game ran very slowly on my computer.   (Not the game speed, I mean my computer's ability to process the game was slow with slow zooms in and out, etc.).  I watched the replay and it was slow at 8x speed, too.  I never had a problem before.  I rebooted and tried again and had the same problem.  I am becoming convinced that I have a problem with regular Sins because the same thing has happened in the past.

So, I wondered whether I would have the same problem in Diplomacy.  So I loaded up Diplomacy to watch a 5v5 replay--no problem at all.  Has anyone else experienced something like this?  What could be causing this?

<Edit> I loaded up an Entrenchment replay and have the same problem in Entrenchment.  The replay was dated from mid-July, so this development is a recent problem because I didn't have any difficulty playing in mid-July.