FFMPEG based Theora Video Decoder performance??

Question

Hi,

I am in process of porting and optimization of the theora video decoder in the ffmpeg-0.5 package to ARM-Cortex-A8 -Neon processor @ 667 MHz. I am looking for some target estimate for frames per second the decoder library alone should achieve after full optimization (C level and Neon assembly / Intrinsics) for 720x480 Progressive content for a 2Mbps stream. I have a Real Video 9 decoder on cortex-A8 which gives around 40 fps for the same stream above.(720x480, 2Mbps) How can i extrapolate this data based on relative complexities of RV9 and Theora and get a fps estimate for theora decoder Cortex-A8?

I am aware the performance depends upon the cache configuration of the h/w, etc...,but any Any pointers will help.

Thanks,

-AD