https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70452
--- Comment #11 from Patrick Palka <ppalka at gcc dot gnu.org> --- gcc 5 shows: Execution times (seconds) phase setup : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 1311 kB ( 0%) ggc phase parsing : 2.10 (100%) usr 0.28 (100%) sys 2.37 (100%) wall 516276 kB (100%) ggc |name lookup : 0.03 ( 1%) usr 0.00 ( 0%) sys 0.02 ( 1%) wall 83 kB ( 0%) ggc |overload resolution : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 628 kB ( 0%) ggc preprocessing : 0.01 ( 0%) usr 0.06 (21%) sys 0.06 ( 3%) wall 2048 kB ( 0%) ggc parser (global) : 0.04 ( 2%) usr 0.04 (14%) sys 0.09 ( 4%) wall 16180 kB ( 3%) ggc parser function body : 2.05 (98%) usr 0.18 (64%) sys 2.22 (93%) wall 498040 kB (96%) ggc TOTAL : 2.10 0.28 2.38 517605 kB trunk now shows: Execution times (seconds) phase setup : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 1%) wall 1287 kB ( 1%) ggc phase parsing : 1.31 (100%) usr 0.21 (100%) sys 1.51 (99%) wall 203649 kB (99%) ggc |name lookup : 0.02 ( 2%) usr 0.00 ( 0%) sys 0.03 ( 2%) wall 81 kB ( 0%) ggc |overload resolution : 0.04 ( 3%) usr 0.00 ( 0%) sys 0.04 ( 3%) wall 628 kB ( 0%) ggc preprocessing : 0.02 ( 2%) usr 0.08 (38%) sys 0.08 ( 5%) wall 2048 kB ( 1%) ggc parser (global) : 0.02 ( 2%) usr 0.02 (10%) sys 0.06 ( 4%) wall 7735 kB ( 4%) ggc parser function body : 1.27 (97%) usr 0.11 (52%) sys 1.37 (90%) wall 193854 kB (95%) ggc TOTAL : 1.31 0.21 1.52 204947 kB Hmm, peak memory usage is still about 50MB more than 4.9...