Alan,
It could be but I'd imagine it is not significant. I'll measure the raw data throughput on the board later. They say the read through put on the A-board is something like 2.5MB/sec. Assuming this ideal bandwidth achieved, the JMV file is about 1.5MB, so half a second is spent on reading over 20 seconds or so play time.
From a USB memory in VFAT, it seems to be able to do 13MB/sec or such.
And, Linux uses free memory space as file buffer cache (and OLPC will have some memory-based filesystem (tmpfs). If I read a file from cached data, Squeak can do over 70MB/sec.
Our MPEGPlayer seems to spend so much time on updating sliders and buttons and invisible subtitle. Only about 60% of time seems to be spent for decoding (about 30%) and displaying (about 30%). We could do some more optimization.
-- Yoshiki