Do those solutions work for you?
Yes, change is very very clear !
Does changing the thumbnail size in layers panel have an effect on the performance?
I did not notice any visible differences, the only solution (for me) is to put "no" ... unfortunately
I'd start with doublechecking your video card driver is up to date. Even one version back can sometimes cause issues.
The latest available (not beta) at NVIDIA
I did these tests on the same computer. I noticed that if I put also on as "no" in CS5, it is also much faster.
My question, why such a difference to load the exact same file to a temporary file and why also huge with CS6 x64. It's as if I was using the x32 CS5.
I did the test and that's exactly the right solution. Actually if I put "128" (which is default in CS5) instead of 1024 (which is default in CS6), charging is as fast as with CS5 and in addition the temporary file is also much less fat (the same size with CS5 !)
I note that the speed problem that I mentioned is not really a problem, but only because of a difference in configuration "default" of the two versions.
Still the problem of activation or none of "Thumbnails" which creates delays (even unable to work properly) to move layers or group. Problem mentioned (and shown in video) on the link I put in my first message !