Interesting that it's faster to kill Kraid than to use the Norfair back door. I guess the lava swim requires too many energy tanks for that route to be worthwhile?

There are plenty of e-tanks on your way to norfair and another in the lava, that's not a problem at all. But to use the backdoor, you must: - make a larger detour for charge beam - get grapple - sequence break a super missile not from spore spawn (which is slow) - get slowly through the lava and bomb your way through the speed booster room If we time both routes from Varia to Speed Booster and include the times for grabbing charge beam, we'll notice that the Kraid route is ~103 seconds faster (406 vs 509 seconds). Now you might think that exiting through the back door gets you closer to the norfair power bombs, but bombing though the SB room and traversing the lava again is actually slower, the kraid route gains another ~12s. The Kraid route will end up with less e-tanks and without grapple, but instead it'll get more SM packs and Spazer. I got the times by comparing with the any% run I linked here. That run appears to be less optimized than hoandjzj's, but it's very unlikely to improve the norfair route by ~115 seconds. What bothers me is that the other run managed to skip both the L3 and the L4 lock. Hoandjzj got both, each being a large detour. Skipping them would require the XRay scope (almost on your route) and some detours inside the space pirate ship, but it still appears to be faster to skip them.