Using it results in the browser slowing down. Please use something else instead of it.
If you know a viable replacement I am happy to experiment with it.
Problem is they're not actually using MutationObserver but instead triggering looking at the whole DOM again every time it changes.
edit: I'm removing this site from my oAuth again so who knows if I'll orphan this account.
These performance issues should be fixed now, let me know if you still have problems.