Here's the
video (removed the first casual clear, of course)!
For future reference, here's what could be improved (under realistic circumstances):
Stage 1
Milk a handful more enemies from the hatches. Those are worth peanuts, but it's there.
Ideally you can destroy two turrets while taking out the first boss, that requires luck, though. If you're unlucky, the core spawns in an isolated area and you don't get any additional turret at all, the best you can get is two turrets, I believe. That's also negligible in the long run.
Stage 2
I milked the Titan for a few of its missiles already, but I could've gotten more points, I believe. Again, peanuts.
And once more a slightly better milking from the hatches.
Second boss fight was really bad (for safety reasons). You can get over 20,000 points more out of it, probably requiring a different suit.
Stage 3
I only got one mine from the Barons before the mid-boss since those guys immediately escape afterwards. You can get one from each. That's another 20,000 points.
While I am extremely satisfied with how the milking turned out on the third boss, it could be better (see below).
Stage 4
Milk the first phase of the mid-boss for a few more missiles. This is yet again a minimal amount of points.
Get a slightly better time at the boss. I was nervous wrack at that point and didn't use the special attack properly.
Stage 5
Destroy several more spheres from the mid-boss. Didn't even look into that all that thoroughly, but again, I was too nervous at that point, regardless.
Don't miss two platforms that are easy to get and worth 10,000 points each!
Get a few Titan missiles for a pitiful amount of points at the end of the game.
Now, this would ideally net a score over 4.6m, but it's still under the WR by a considerable amount. Unless there's some sort of a bug that gives you extra points for doing something esoteric, I would assume that there must be a way to squeeze a lot more points out of the third boss. The spheres will spawn faster the quicker you destroy them - if you let one sphere pass by, however severely damaged, it will continue its merry-go-round before a fresh set appears. My initial thought was that a Baron suit or the Garland itself might be faster than the Grain Beat since they offer true point-blank auto fire capabilities that the latter lacks, but it's apparently either not the case or completely unrealistic to pull off (the Baron has one hell of a time actually doing damage to the boss, too!). But this is pretty much the only spot in the game that's left for big points. Sure, if you somehow optimize the process of taking over fewer mechs you might get a few thousand points more, but we're still talking about roughly 100k here. No idea where those are...
I will say, however, that I am really happy with my current score.