AVR-GCC versions comparison By Dmitry K. 

Flash and Stack values are in bytes. 

Time units are in CPU clocks. 

All values were simulated by simulavr. 

Times and sizes are presented without initialization of function args.

Results 

AVR:                             at90s8515                 atmega8      
avr-gcc version:         3.3.6 3.4.6 4.0.4 4.1.2   3.3.6 3.4.6 4.0.4 4.1.2  
--------------------------------------------------------------------------
dtostre(1.2345,s,6,0)
                 Flash:   1024  1024  1120  1212     954   954  1038  1112  
                 Stack:     15    15    15    17      15    15    15    17  
                 Time:    1199  1199  1289  1315    1060  1060  1123  1155