Sets the delay that will occur after each keystroke sent by Send and ControlSend.
SetKeyDelay Delay, PressDuration, "Play"
Time in milliseconds. Use -1 for no delay at all and 0 for the smallest possible delay (however, if the Play parameter is present, both 0 and -1 produce no delay). Leave this parameter blank to retain the current Delay.
If SetKeyDelay is never used by a script, the default Delay for the tradional SendEvent mode is 10. For SendPlay mode, the default Delay is -1. The default PressDuration (below) is -1 for both modes.
Certain games and other specialized applications may require a delay inside each keystroke; that is, after the press of the key but before its release.
Use -1 for no delay at all (default) and 0 for the smallest possible delay (however, if the Play parameter is present, both 0 and -1 produce no delay). Omit this parameter to leave the current PressDuration unchanged.
Note: PressDuration also produces a delay after any change to the modifier key state (CTRL, ALT, SHIFT, and WIN) needed to support the keys being sent.
The word Play applies the above settings to the SendPlay mode rather than the traditional SendEvent mode. If a script never uses this parameter, the delay is always -1/-1 for SendPlay.
Note: SetKeyDelay is not obeyed by SendInput; there is no delay between keystrokes in that mode. This same is true for Send when SendMode Input is in effect.
A short delay (sleep) is done automatically after every keystroke sent by Send or ControlSend. This is done to improve the reliability of scripts because a window sometimes can't keep up with a rapid flood of keystrokes.
Due to the granularity of the OS's time-keeping system, delays might be rounded up to the nearest multiple of 10 or 15. For example, a delay between 1 and 10 (inclusive) is equivalent to 10 or 15 on most Windows XP systems (and probably 2k).
For Send/SendEvent mode, a delay of 0 internally executes a Sleep(0), which yields the remainder of the script's timeslice to any other process that may need it. If there is none, Sleep(0) will not sleep at all. By contrast, a delay of -1 will never sleep. For better reliability, 0 is recommended as an alternative to -1.
When the delay is set to -1, a script's process-priority becomes an important factor in how fast it can send keystrokes when using the traditional SendEvent mode. To raise a script's priority, use ProcessSetPriority "High". Although this typically causes keystrokes to be sent faster than the active window can process them, the system automatically buffers them. Buffered keystrokes continue to arrive in the target window after the Send function completes (even if the window is no longer active). This is usually harmless because any subsequent keystrokes sent to the same window get queued up behind the ones already in the buffer.
The built-in variable A_KeyDelay contains the current setting of Delay for Send/SendEvent mode. A_KeyDuration contains the setting for PressDuration, while A_KeyDelayPlay and A_KeyDurationPlay contain the settings for SendPlay.
Every newly launched thread (such as a hotkey, custom menu item, or timed subroutine) starts off fresh with the default setting for this function. That default may be changed by using this function in the auto-execute section (top part of the script).
Send, ControlSend, SendMode, SetMouseDelay, SetControlDelay, SetWinDelay, Click
SetKeyDelay 0