sharpshooter question

you know Twains Arc? that mid sharpshooter ability? i have a couple questions about it for any forum geniuses out there.

1. Is the fire rate of the Arc affected by the attack speed of the weapon? On the wiki it says it taes 2 seconds for it to charge but after a bit of my own testing i feel like it changes when its super fast vs super slow
2. If it is, then is there a cap or limit of sorts? kind of like how theres an optimal attack speed for ophanim orbs?

thanks

 

im 99% sure it isnt, but even if there was going basically hmelee would be optimal anyways since its not that great of a difference