Well thanks, but unfortunately it doesn't work that way on windows.
So finally, I installed the beta, which replaced the 3.0 (11.0), to experiment.
For the things I use MM for, I see no real difference ; speed looks similar, and these "freezing" moments are still there, and drive me crazy (for example I load a model, something like 2Mpolys, textured, once it's fully loaded, use the select tool and select a few patches, I want to change the viewing angle, and suddenly everything freezes for something like 30 seconds or more) Dreadful !
Oh yes there is one difference, in the beta version I cannot input values with decimal points (in the transform/translate dialog box). I haven't tried anywhere else, but I suspect this is true everywhere. FYI I have a french keyboard, so that decimal point and decimal comma are normaly inverted, the system takes care of that. But here nothing works, neither the numpad point, nor the regular point, nor the comma.
I have re-installed the 3.0 version, and it replaced the beta. The last point is back to normal. Everything else is unchanged.
And the .mix files are
My system is : Win 7, Corei7-6700 @3.4GHz - 64Gb Ram - TitanX graphics card with 12Gb Ram (and latest driver)