Improve efficiency of collection handling

[46bit]

Right now, the presenters recreate a lot of data every time the number of entities changes. For something like shotgun projectiles this means an enormous amount of work goes on.

It would be better to store an expanding/contracting amount of data. Either arrays which double in size as-needed, and halve if not needed to be so big for awhile. Or multiple arrays (sharding-style.)

This might improve subtle strange rendering behaviour and flickering.