In both Brood War and Starcraft 2, I played as zerg, and built a couple of hatcheries and 6 zerglings. I would then hit the attack button, hold it over the hatchery, and then hit both the start button on my stop watch, and my mouse button to attack simultaneously. I would hit the stop button on my stop watch when the health of the building hit 0.
SC:BW Results
Before Adrenal Gland Upgrade (AGU)
18.9 seconds
18.7 seconds
18.7 seconds
Average: 18.77 seconds
After AGU
13.1 seconds
12.9 seconds
13.1 seconds
Average: 13.03 seconds
SC2
Before AGU
30.5 seconds
30 seconds
30.7 seconds
Average: 30.4 seconds
After AGU
25.5
25.5
25.5 (yeah, I couldn't believe it - exact same every time. I couldn't have done that again if I tried)
Average: You figure it out.
The data that I collected confirmed that the attack speed increase for SC2 was indeed 20% faster (the math comes out to be about a 19.4% increase or so), but it was a far cry from the crackling attack speed upgrade, which comes out to be about a 44% increase in attack speed. I want my cracklings back...
On another note, I did notice with patch 9 that zerg buildings now bleed when injured. And I also had a weird graphic issue, and I'm curious if anyone else has seen this - before the patch buildings that I had queued up to build were semi-transparent, but with the new patch, when I queue up buildings they appear as the fully built structure (at least with zerg).