You are working with a FREE compiler. It seems you are learning the old adage "you get what you pay for".

I disagree, I use SDCC and it's building very small programs and optimizing them quite well (not as good as my assembler code, but C Compiliers never are as good as good assembler).

I think the problem may also come down to treating programming using C on a microcontroller like you were using C on a PC, using floating point and int's instead of unsigned chars, using big stack variables etc.

These are always traits of not understanding the hardware your program is going to run on.

If you have a better understanding of how the compilier is doing things, and how you can write your code so the compilier can make full use of the optimizer you will get very good code out of SDCC.

I suggest reading the manual that comes with SDCC, it has a tips section where it tells you how you can help the compilier do it's job.

Chris