getCommitteeAssignment performance issue

[dapplion]

Describe the bug

getCommitteeAssignment() will loop through the entire shuffled index list (worst case) for every validator connected to the beacon node.

lodestar/packages/beacon-state-transition/src/allForks/util/epochContext.ts

Lines 440 to 449 in 16b856f

	const epochStartSlot = computeStartSlotAtEpoch(epoch);
	for (let slot = epochStartSlot; slot < epochStartSlot + SLOTS_PER_EPOCH; slot++) {
	const committeeCount = this.getCommitteeCountAtSlot(slot);
	for (let i = 0; i < committeeCount; i++) {
	const committee = this.getBeaconCommittee(slot, i);
	if (committee.includes(validatorIndex)) {
	return {
	validators: committee as List<number>,
	committeeIndex: i,
	slot,

Expected behavior

Find a more efficient approach