WIP: Event manager allocations

This is still very much a work in progress, so I'm not requesting that anyone review this yet. I'm trying to get rid of the small unneeded allocations in the event manager. So far, I'm observing a 15-20% reduction in allocations. I've not seen this improve performance, but I suspect that as I push the allocations down even lower, the reduced indirections that accompany these changes will lead to some measurable performance gains.