The fireworks that are caused by leveling up and using skills in MCMMO create a large amount of lag for most players. I hope the fireworks can be fixed to where they do not lag or disabled entirely.
There is an option in the MCMMO config file for disabling fireworks. I think that would be a good idea.
When mining unless i click right click it doesn't activate the MCMMO Super Breaker / Firework so i would just recommended when mining not to right click.
The problem isn't when you activate an ability, the problem is when you get 100 levels of a skill and a firework goes off. Also the problem isn't actually the firework itself, but there is a known bug with MCMMO that it causes a lot of lag when it tries to launch that firework.
Fireworks have been disabled for normal occasion and will be disabled following the next restart, thanks for the suggestion!