Great work; thank you.
I think this (FAQ) would be a fantastic place to have the "standard" RPI tweaks listed since it's already a great source and it ties in.
Of course with the disclaimer that the power supply must be confirmed as being powerful enough before "safely" or "unsafely" overclocking.
The config.txt tables on the link have not been updated, unfortunately, but there has been some work done by people in the forum to sort out the details. (I only overclock the CPU, since the GPU handles video files no problem, but with the single tweak of going up to 900Mhz, I know it's not optimal)
Also suggested for speeding up the default skin:
-Disable "Recently Watched" (Settings > Skin > Home Window Options > disable "Show Recently Added Videos")
-Disable Fanart (Settings > Skin > Background Options > enable "Hide Background Fanart")
-Disable reading thumbnails from the files (Settings > Video > disable "Extract thumbnail and video information")
-Note: recent builds of OpenELEC enable some more obscure optimizations, like DDS thumbnails of a small size
And one of the bigger white whales to speed up the interface: switch away from SMB (Can take up to 20% of the CPU in some cases)
Also, the DTS Audio issues are not just limited to NFS, as some of the higher bitrate 5.1+ DTS streams actually max out the CPU when it has to transcode them.
With the right TV, the Raspberry Pi can pass along the DTS stream untouched, meaning no more stuttering due to transcoding.