Ya, VBScript macros were not meant for button mashing, especially with long key sequences.

VBScript has a huge overhead, and I would STRONGLY suggest not using those for frequent key presses. I only use them for occasional things like solo assist (setting targets pre-pull in an instance) or buffing.

For the Simple macros, I stick with 1 or 2 keystrokes and I'm able to mash them non-stop with no problems.