The spins per second counter reads 477 as always, but the autoplay spins faster than that when double-time is on, far past the limits of physically possible...
Normal speed:

Seems about right...
Double-time:

Whoa, that's way more spins! Probably something to do with autoplay spinning 1.5 times as fast as usual to go along with double-time despite it not being actually possible normally?
Normal speed:
Seems about right...
Double-time:
Whoa, that's way more spins! Probably something to do with autoplay spinning 1.5 times as fast as usual to go along with double-time despite it not being actually possible normally?