Matthwe's ares NG+ hardcore run somehow managed to skip enemy spawns in the first lightning spike room in stage 6 accidentally, which saved him a few seconds. How is that possible?

If we can figure out exactly what location the game checks to start spawning the enemies, then it might be possible to skip the spawns, in much the same way that red key skip works.

Some bosses can be shortened considerable via solar flare (Goliath and healthbar1/phase2 minos cannon, primarily).

Many others simply have attacks that waste your time (stage 2, stage 4, stage 6). Has anyone found a reliable way to kill those peskier, time wasting bosses within just a few cycles? Stage 2 and 4 in particular are annoying because they spend so much time being inaccessible or invulnerable.

The only few damage-increases I've found so far are solar flare for multi-body enemies and blazing fist for enemies that stay slow enough to be hit (but then it has significant cooldown, and stops if you are hit during startup).