an online tracker or an offline tracker?

Hi, thanks for your great work!

I am just wondering is this an online tracker or an offline tracker? After the reading of the whole paper, I feel like this should be an offline tracker, but there's also a 'Hz' metric in the evaluation tables. Therefore I got confused, if offline, how the Hz is calculated? And also as far as I understand, Tracktor is actually an online one, right?

Thanks!