Pixolator’s promise of a timing zscript here set me thinking and I came up with this. It’s pretty basic but may be useful.
It works pretty much like a stop watch. Start and stop it at any time during a ZBrush session. It doesn’t need to stay loaded - simply press Start to start the timer and you can then call other zscripts or whatever. Just reload it when you want to Stop it or see how much time has elapsed by pressing the Time? button. Press ‘Clear’ after stopping to reset timer. The time setting is saved between ZBrush sessions (whether ‘Stop’ is pressed or not) as long as the timer is loaded when exiting ZBrush.
The code is included in the zip.