How to reproduce:
Start VS with vanilla config, dock, look at Weapons - they have bogus statistics affecting lots of irrelevant fields.Look at overdrive parameters - they set a lot of fields to "-100%" too. Fields that should be affected are set to wrong values.
Now set "physics" to "realistic" in setup. Look at Overdrives - now that they cannot overcome "-100%", they have negative effects, slowing the ship down. Installing one affects ship info and actual gameplay as calculated, rather than as it should.
Also, should mult_ -type upgrade's own parameters be adjusted with game_speed at all?