trust me there are better discussions than that one
basically if you are not a programmer then i wouldnt bother trying to speed anything up, if you are we could use a bit of help
SD's a problem scince we dont have the full documenation for the SD card and will most likly never will, however some basic SD stuff went into the last mainline kernel which is nice, i cant wait to see how it will effect things
if i remeber corectly there is a flag you can pass to the SD module (both on 2.4 and 2.6) try using modinfo <module name without .ko> on the SD card modules (hint use lsmod)