Repeating Xbow attack speed - broken?

[AtomicMew]

Excuse me if this is common knowledge in arti circles, but according to a bit of testing on the training dummy, attack speed boosts don't seem to do anything at all. Is this wrong? WAI?

Here are some results I pulled with a stopwatch:

level 20: 16 BAB
No boosts: 26 volleys/42 s = .619
Abbot quiver: 26 volleys/42 s = .619
armor of speed boost: 25/40 s = .625
armor or speed + haste boost 30%: 13/20 s = .65

Keeping in mind 1-2 sec human error, these numbers are almost the same. Armor of speed + haste boost should be 22% + 35% = 57% faster according to the game log, but it seems at best 5% faster (if at all considering measurement error).


edit: here are some numbers for bow:

No boosts: 40 attacks/41 s = .976
Speed: 40 attacks/37 s = 1.08
speed + haste boost: 25/20 s = 1.25

The difference for bow is obvious and beyond the margin of error.