It runs at 8.125 MHz, which was chosen because it's 1/8th of the 65 MHz pixel clock necessary for 1024 x 768 @ 60 Hz VGA video. The real Plus runs at 7.83 MHz, so everything is a little bit too fast.

One strange thing is that loading data from the virtual "floppy disk" is unexpectedly slow. I haven't timed it, but it seems slower than even a real Mac Plus, which is odd because there are no delays here for track-to-track head movements. Or maybe it's the general execution speed of the computer in general that feels slow, I can't be sure. When it's working better, I'll run Speedometer or something on it.