On big slides it would be better to make each slide have a state

[cli-ish]

This could increase performance since every thread has to start with a slide.
Currently, each thread runs to its position without taking screenshots, but this still requires a large amount of Js, which could be avoided if the thread could only play the state that is passed.

[C0D3D3V]

Hi, nice work you have done :)
In my bbb-dl I just search the beginning of a slide and start from that position, that should be pretty safe, since you can not show two slides at the same time in bbb.
But using states would be a good improvement, because you can then split even one slide into multiple threads.