[WorldMaker]

Specifically implied there is that one of the technical complaints was "draw distance" at speed and issues with "pop in" where things that should be visible aren't visible until "too late" after when they should be. If you build and tune a game engine for traveling at horse speeds and then add in vehicles that move three/four/five times as fast and some of them can fly, that puts a lot of strain on however you tuned the engine for drawing things at horse speeds and the expected results line up with many of the complaints about "draw distance" at speed and issues with "pop in".

Which is not to say that that was definitely the reason for some of those issues existed, but it does line up with what you would expect adding faster vehicles to an engine that hadn't been prepared for that.