[yoklov]

I think it’s not 500 deletes, but it’s certainly not great. There is definitely an index. If you can repro this, you should file a bug for it, I’ve noticed it being slow too, but couldn’t repro it recently. If you file a bug for this, you can CC me (tcsc at mozilla dot com).

[liability]

I believe/guess it manifests most noticably when you have a large amount of history, so it might be hard to repro with a fresh profile. I'm on the road away from a real computer, but when I get back I'll give it a shot.