at home why can't you use the command line options? i think there is no possibility changing the optimalizations of gcc during compiling.
as i told you, i use 'register' keyword before variables and have a look at the compiled binary (at home). hopefully the judge's gcc generates same or very similar binary
i'am always interested in a speed challange (if i can solve the problem. but i won't use assembly, the source is ugly enough already)
P10282: 0.230 sec