Thief %/s (KMS Unlimited and GMS Tempest)

The last hit should be affected by booster.

So you are saying that the last hit on Faster(2) is 540 ms? I guess that sounds more accurate.
With this delay I am getting numbers close (albeit 150~200% lower) than yours, for all calculations so around a 2.25% calculation difference, no biggy.

On another topic, it seems like Assassinate in-game is much slower than expected, I thought it was me lagging but this buddy of mine had the same results.

EDIT: Without Dark Sight it works as expected 1170 ms.
With Dark Sight I am getting 1500 ms, 1470 at least if you count that maybe I was lagging although I kept getting 1500.
20 Nates+Dark Sight in 30 seconds.