Ship icon movement speed

I took a breather from SEV and am back. I install 1.66 on a clean install. But when I play, the icons for the ships move around the sytems INCREDIBLY slowly. Like one and a bit hexs per second.
I've tried changing the "movement replay movement icon speed" and "movement replay rate" to "very high", but they make no difference (well, they make a difference, but it is barely perceptible). A little digging finds "Main System Display Icon Move Speed Points Per Second Very High" in settings.txt, which I increase by a couple of 0s to 20000000.0, but it makes no difference.

I uninstalled and tried a fresh install without the patch (because this problem wasn't there in 1.44 - which is what I was using when last playing), and sure enough, my ships zip around the galaxy just fine.

More digging finds 1.53 added this, which seems like a likely culprit:
'Added - "Movement Replay Icon Movement Speed" to control the "System Icon Movement Speed" during a movement replay.'

Does anyone know how to resolve this problem short of not using a patch above 1.53? Because waiting for lethargic ships to cross space is tedius at turn 5. I dread to think what turn 100 would be like. :-/

Note - I am getting constant frame-rates of 60fps, so it's not that.

Thanks