Lower your performance settings all the way. Then try your route again. If it works, you can try increasing the settings little by little. If lowering the settings all the way didn’t help, you may need to restore the route from backup.
By Hi res, do you mean HD Terrain? You don't have to build in HD terrain. You can still use 5 and 10 meter grids. Later versions of Trainz have changed what the settings do. I found I had to lower my settings to preform the same as earlier versions.
It was a limited time offer. The routes you create in Plus is supposed to be compatible with PE, however if you create a HD Terrain route,PE will have to convert to 5m grid for you to edit.
Why HDT? Because people asked for more realistic terrain and better shadows. The narrower cuts and fills are visible from the cab.
People want more textures, but that affects performance and how much space is used on hard drives. Already people complain about how much space is used when...
What route are you running? My m1 Mac mini isn’t that bad. What is version? How much ram do you have and how much space free on your hard drive? I don’t think it is doing anything deliberately wrong. I have been running using 8gb ram on my other computers and 16gb on my mini. Is everything up to...
What frame rate are you getting in your route under Trainz 22? They changed the meaning of the settings, so you may need to dial down your performance settings a bit. I ultra performance in 19 is equivalent to high in 22.
The Mac do fine for Trainz. They don’t optimize Trainz as much as they do Windows but they are making it better on the Mac. Turf-FX is still in beta I think, but ASi and Metal optimizations have been done. More should be done, but it works and I think doing well.
One thing to keep in mind...
The betas will keep going. I just rename the application, so I know which install I am starting. The trainz plus beta stream install has beta in the title.
With users pushing them to be more realistic, content had to be more complex as there are more options. I have yet to see any one propose how to make it easier. They don’t have the ability to make a utility to make it easier. Those who do make content don’t want to document what they do, so...