Here is some data for testcase from PR8361: -O0 -O1 -O2 -O3 ---------------------------------------------- GCC 3.2.3 28.98 54.27 70.90 73.9 GCC 3.3.2 30.13 54.59 76.39 77.89 mainline 31.91 113.22 105.29 106.30 w/o checking 26.37 90.78 87.88 89.16 tree-ssa 32.60 71.49 93.78 99.14 Mainline (w/o checking) is nearly twice as slow as 3.3.2 for -O1. Gerald