A PocketMine-MP plugin implementing vanilla hopper behaviour.
A hopper will continue to tick itself every transfer.tick-rate (default: 8) game ticks only if there is a container above it or on the side it's tube is facing.
When not in use, a hopper (or more precisely, it's behaviour) per se will NEVER contribute to any additional server load.
However, (item-sucking.per-tick number of) dropped items check for hoppers below them every item-sucking.tick-rate (default: 1) game tick(s).
Reconfiguring some variables may help reduce server load. The default configuration values for transfer.tick-rate and transfer.per-tick reflect vanilla.
Tripling transfer.tick-rate as well as transfer.per-tick would reduce the frequency at which containers are scanned by 3x at the cost of transfers getting delayed by 3x.
# Optimization: instead of transferring 1 item every 8 ticks, transfer 3 items every 24 ticks.
transfer:
tick-rate: 24
per-tick: 3