I found the saving overhead about 380ms.
Without disabling saving, I would have the overhead for 128 saves and 127 reads to do what I want, which say adds up to an extra 96 seconds.
It would work something like this:
-take first bias
loop 127 times:
-take bias, stop at raw hook
-read in previous bias, sum with current raw buffer
-if last loop, shift right >> 7
-raw continue, save summed dark
end
The sums will fit in a signed 16bit, and 128 frames should be enough for an almost perfect master bias.
As for saving small jpgs for less overhead, it actually takes a bit longer to make a smaller picture because of the resizing step, which I assume is nothing compared to i/o time, which has a minimum because flash writes a page at a time anyhow and page write times are large even if you're writing one page. At least in a theoretically argument.
