It's not actually possible to do a full speed link-up using Supermodel yet. I thought the issue was entirely down to the fact you have to run Supermodel in single threaded mode when you use the network mode, but I can actually run 2 versions of it not linked with the - no-threads option on both at around 55fps. The actual network itself causes the majority of the slowdown, an issue which the Supermodel developers know about and think should be fixable. Some of the members of the Supermodel forum can run multiple (not linked) versions at 60fps with the - no-threads option who have far beefier PCs than me (e.g.Ryzen 9 3950X / X570 mboard with 32GiB RAM and a GeForce RTX 2070), but if you only wanted to run a single system 2 player Supermodel network, you probably wouldn't need anything quite as fancy as that.