You can grab the files straight from here, or head over to the releases tab for simple downloads.
Also included is the raw .ahk file, also viewable at http://pastebin.com/yLJEbMxP
Alt + Backspace -- Toggle autoclicker
Alt + - -- Open options window
(Version number is shown in the "Change Click Speed" window)
While it's running, minimizing the window will, in most cases, cause the application to lag severely. I don't know if it's something I can fix, or if it's a result of sending clicks to a minimized window, but as a solution, just leave the window open in the background.
If it was running fine, and starts lagging:
If it starts lagging for you, hold left-click in the target window until clicking stops, then drag the cursor outside of the window, let go, and immediately click again.
This should clear up the lag, assuming it can run smoothly at that speed in the first place. I have no idea why this fixes it. If I can figure it out, hopefully I can get it in the script, and just keep it running smooth, all the time.
If NIAutoclicker works, but not in specific programs:
Run NIAutoclicker as administrator.
Cheers!