why AutoResetEvent instead of ManualResetEventSlim

[sebas77]

in my code, I moved t o ManualResetEventSlim...not sure if it would make sense to make a PR for it

[RevenantX]

@sebas77 and this gives performance boost?

[sebas77]

it's not about performance, it's about waking up (returning to the thread) precision...it makes sense only on windows though, on linux/android/ios the sync primitives are already precise.