It is very high, way above anything we have today, even ion engines. What you can try, as an experiment, is to load say 100 kg of propellant into the vessel, and, from a circular orbit, see how many m/s you get from it burning prograde or retrograde.
Alternatively, Orbiter is now open-source...
I made a few experiments on my side, that's why I was curious. I had the exact same issues. It looks like the 'order' in which the objects are drawn don't work well with transparency (alpha-channel mapping).
So there was a sale on FS on Steam, I couldn't resist and bought the Premium package.
The installation is beyond anything I experienced until now. The amount of data handled is crazy. But with patience, thorough disk-cleaning, and a glassfiber connection, I made it (circa 20 hours!).
And it...
At Polar Motion, I can say I'm the head of the mighty Testing Department(tm). But I'm also really involved into game design. We're 3 people. :D
And, seriously, though not full-time, we're working 6 days a week, sometimes 7!
Space Station Designer v0.5.25 is out !
On Steam : https://store.steampowered.com/app/1447650/Space_Station_Designer
On itch.io : https://polar-motion.itch.io/space-station-designer-playable-alpha/devlog/711201/space-station-designer-version-0525-is-now-available
To put it shortly, we have...