I had a quick go at benchmarking the Linaro GCC compiler and was presently surprised. The workload was decoding 10 s of h.264 video using ffmpeg with assembly optimisations disabled. This gives the compiler a good workout.
Compared to FSF GCC 4.4.4, Linaro GCC 4.4 is 6 % faster, FSF GCC 4.5.0 is 12 % faster, and Linaro GCC 4.5 is 24 % faster.
Now this is with a sample size of one so the results are not statistically valid, and I haven't told you how to reproduce it so they're not scientifically valid, but the numbers are pleasing none the less.
-- Michael