[Shine]

You guys should mention whether you actually tested using 1080p Hi10P stuff or not to get comparable results. Anything else (even 720p Hi10P) should be playable flawlessly on most non-ancient (and non-Atom, non-Fusion) CPUs in a single thread. Core-i with TurboBoost at close to or more than 3GHz will likely decode everything you can find nowadays flawlessly without the need for multi-threading.

Check task manager while XBMC is playing, too. If decoding is truly multi-threaded, all CPU cores should be loaded similarly high or low. Single-threaded decode causes high load on one core and significantly lower (not zero) load on the other cores. If none of your cores is experiencing high load, then you either have a super-fast CPU or the files you're playing aren't challenging at all to the decoder.

Last not least, if you don't have any Hi10P stuff at hand, make sure to disable DXVA when testing. Using DXVA will leave all your CPU cores idle while the GPU is doing the work. In addition, you migt want to check the h.264 profile of your test files, e.g. using MediaInfo - in case your files are L4.1, they may very well be sliced - which even the non-mt builds above will decode multi-threaded. These builds aren't actually non-mt at all - it's just frame based mt that is disabled for stability, leaving only slice based.