Hrvoje> There is a big difference, and I will repeat it: Hrvoje> With -O3, you give the compiler free hands to do what it chooses with Hrvoje> inlining the functions. The compiler may be Very Smart, but it cannot Hrvoje> possibly know all the XEmacs context. Neither can the XEmacs developers. Programmers are notoriously poor at judging performance issues in the source code they maintain. The particular case of digit_to_number is sad. Inlining the function always saves code size AND execution time, so gcc should inline it with -O2. Hrvoje> On the other hand, with -O2 + inline declarations, you decide against Hrvoje> inlining the functions, except when you say so. Hrvoje> I use Gcc, so `inline' does not have a preprocessor definition. Correct. Project: You could write a program to determine all static functions in XEmacs that are called only once. Then add inline to their function definitions. As an added help for the stupid compiler, make sure the definitions of these functions are located prior to their use in the source code. Martin