At last we can compare IE x86+flash x86 vs IE x64+flash x64 (still preview). X64 version is faster than x86 by an average of 50% through a 50 test benchmark: wwwDOTfavbrowserDOTcom/internet-explorer-9-32-bit-x86-vs-ie9-64-bit-x64/ Now it´s time to MS to REALLY support the switch to x64...maybe silverlight X64 and other stuff.
A preview version of x64 abobe flash player has been released into public which is using the codename "Square". Search the following string in Google to get the download link : Flash Player Square Download