Funny one this as have a published app which when navigating folders needed incredibly quick finger taps to browse through folders. So in essence simple to do for one user (via Control Panel | mouse | Double-click speed).
To program in via GPO interestingly was a bit of a rabbit-hole at first to find, nothing obvious via GPO settings so figured group policy preferences would need to rescue me here. Sure enough in an easy enough spot:
hkey_current_user\Control Panel\Mouse\DoubleClickSpeed – value 700 Reg_SZ
Higher the value the slower the double-click.