gcc is plenty fast at lower optimization levels. And if you want to get funky about it, http://www.bellard.org/tcc/tccboot.html http://www.bellard.org/tcc/tccbo

gcc is plenty fast at lower optimization levels. And if you want to get funky about it, http://www.bellard.org/tcc/tccboot.html http://www.bellard.org/tcc/tccboot.html shows that tcc can compile Linux fast enough for a source-only bootloader. ;-) (The chief downside of compiling with less than gcc -O2 is that dataflow analysis is not done at lower optimization levels, which means that you'll miss some "unused variable" and/or "dead store" warnings.)