Computer slow to transcode high bit rates

[riquez]

Hi there,

I am having issues playing some home made video on the PS3 - its rendered at 1080p 12mbps H264 (mp4)
The PS3 will play regular movies, dvd rips etc over wi-fi & UMS fine. but when it comes to my own videos it plays exceptionally slow (2 or 3 fps) & the audio sounds like "ba-chi-ku-ka"

I assume this is due to my computer unable to transcode the bitrate of these files fast enough.

Is there anything I can do in the UMS settings to improve this situation?

Thanks for your advice

iMac (27-inch, Mid 2011), 2.7 GHz Intel Core i5, 16 GB ram