Interesting... would it also be possible to measure the time the vdp is in CE-ready mode? The less the better!
OpenMSX recently added a feature where you can trigger a probe breakpoint when CE changes, it will be in their upcoming 16.0 release, or a recent development build. My profiler script can also hook into that.
OpenMSX also has an OSD widget built-in where they show this information on screen:
toggle_vdp_busy Enable (or disable) display on the OSD how busy the VDP is
