performance pass

[halfcyan]

i just wanted to do a larger pass of everything performance-wise since small improvements add up in a system like this

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[halfcyan]

added the benchmarking stuff to see how much this improves stuff and uh. wow.

VM count	Before: full scan	After: delta construction	Approx. speedup
10	116 µs	51 µs	2.3x
100	752 µs	41 µs	18.4x
1,000	5.91 ms	42 µs	140x
10,000	57.83 ms	41 µs	1,412x
100,000	567.92 ms	41 µs	13,795x

[halfcyan]

the biggest thing is that the heartbeat resource calc changed from O(VMs) to O(1) which is massive