These are the average compile times for compiling a file in a set of
100 randomly selected files: (time values in seconds)

            gcc 4.4  gcc 4.6  gcc 4.7  clang 3.0  clang 3.1
-fs-o -O0   0.450    0.458    0.501    0.449      0.439
-O0         0.624    0.631    0.684    0.504      0.494
-O0 -g      0.722    0.727    0.781    0.661      0.653
-O2         0.811    0.803    0.874    0.603      0.597
-O2 -g      0.916    0.979    1.06     0.809      0.809


These are the average compile times for compiling a file in the set of
the 10 files that are slowest (as when compiled with gcc 4.4 using
-O2) to compile:

            gcc 4.4  gcc 4.6  gcc 4.7  clang 3.0  clang 3.1
-fs-o -O0   2.18     1.70     1.86     1.70       1.66
-O0         5.87     5.33     5.71     2.90       2.85
-O0 -g      6.71     6.19     6.61     4.00       4.08
-O2         11.9     10.8     12.0     6.72       6.80
-O2 -g      13.2     13.6     15.1     9.57       9.78