I've done some more hacking at boost signals; it looks like inlining parts of named_slot_map_iterator help. Here are my timing results (using the Jody Hagins timing code) before: ===== 1000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 1000 0.0031 0.0002 10 100 0.0009 0.0001 50 20 0.0012 0.0001 100 10 0.0007 0.0001 250 4 0.0007 0.0001 500 2 0.0007 0.0001 1000 1 0.0010 0.0002 ===== 10000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 10000 0.0317 0.0022 10 1000 0.0097 0.0008 50 200 0.0073 0.0006 100 100 0.0070 0.0006 250 40 0.0074 0.0006 500 20 0.0068 0.0006 1000 10 0.0114 0.0008 5000 2 0.0114 0.0028 10000 1 0.0118 0.0031 ===== 100000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 100000 0.3207 0.0219 10 10000 0.0934 0.0077 50 2000 0.0714 0.0065 100 1000 0.0685 0.0065 250 400 0.0677 0.0071 500 200 0.0752 0.0062 1000 100 0.1548 0.0088 5000 20 0.1962 0.0457 10000 10 0.1849 0.0451 50000 2 0.1554 0.0424 100000 1 0.1166 0.0297 ===== 1000000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 1000000 3.2411 0.2233 10 100000 1.0952 0.1057 50 20000 0.9700 0.0843 100 10000 0.8360 0.1601 250 4000 0.6917 0.0638 500 2000 0.7075 0.0641 1000 1000 1.1954 0.0746 5000 200 1.1925 0.2886 10000 100 1.1888 0.3132 50000 20 1.2021 0.3007 100000 10 1.1987 0.3113 500000 2 1.2452 0.3346 And here are the results afterwards: ===== 1000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 1000 0.0018 0.0002 10 100 0.0006 0.0001 50 20 0.0005 0.0001 100 10 0.0006 0.0001 250 4 0.0004 0.0001 500 2 0.0004 0.0001 1000 1 0.0008 0.0002 ===== 10000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 10000 0.0219 0.0023 10 1000 0.0060 0.0008 50 200 0.0040 0.0006 100 100 0.0045 0.0006 250 40 0.0045 0.0006 500 20 0.0061 0.0006 1000 10 0.0081 0.0012 5000 2 0.0094 0.0029 10000 1 0.0093 0.0028 ===== 100000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 100000 0.2100 0.0214 10 10000 0.0608 0.0078 50 2000 0.0460 0.0080 100 1000 0.0439 0.0068 250 400 0.0424 0.0077 500 200 0.0459 0.0064 1000 100 0.0920 0.0079 5000 20 0.0921 0.0299 10000 10 0.0947 0.0303 50000 2 0.0946 0.0316 100000 1 0.0938 0.0307 ===== 1000000 Total Calls ===== Num Slots Calls/Slot Boost Lite --------- ---------- ------- ------- 1 1000000 2.0642 0.2303 10 100000 0.6071 0.0828 50 20000 0.4717 0.0667 100 10000 0.4610 0.0656 250 4000 0.4508 0.0645 500 2000 0.4464 0.0661 1000 1000 0.9111 0.0764 5000 200 0.9358 0.3028 10000 100 0.9399 0.2963 50000 20 0.9330 0.3003 100000 10 0.9357 0.3001 500000 2 0.9455 0.3014