Nasm Nasmus | Testing the lag caused by hoppers on vanilla and spigot @nasmnasmus866 | Uploaded 9 years ago | Updated 45 seconds ago
In this video I find out that Spigot can handle about 4 times as many hoppers with the same amount as lag compared to vanilla 1.8.

Also, putting furnaces on hoppers in Spigot actually increases lag, it does not decrease it like it does in vanilla.

Vanilla 1.8.3 does not offer much improvement in regards to hopper lag in comparison with vanilla 1.8.

Putting furnaces on hoppers will decrease the lag caused by hoppers by around a factor 2.

Finally, on Spigot, a zombie causes around 200 times as many lag as a single hopper.

The video's I talked about:

Accidental Games - Testing Hopper Lag Reduction
youtube.com/watch?v=qEi-tKrxDNk

Peppermint - In-Game tps counter
youtube.com/watch?v=MWgL60xYUJA