I experience the same problem, but only when in the menu/setup phase of the game. Once I go into the game, my GPU runs at about 50%.
I also sometimes use a Mac, but itâs a Mac Pro âcheesegraterâ from 2010 upgraded with Xeon X5690 6 core 3.46ghz processor, 32GB ram and Radeon RX580 8GB and MacOS Big Sur. The GPU fans spin up a lot but the CPU does nothing much at all.
Frame rates stay smooth all the time running 4K resolution at highest detail. I just suspect the laptop macs get hot easily. While the big tower desktop macs run much cooler.
On the other hand my other Mac which is a November 2014 Mac Pro 6,1 âtrash-canâ with 12 core 2.4ghz, 64GB ram and dual D700 GPUs will run hot if I use it for Zwift. Its fan will run fast. But itâs a very unusual powerful but small computer.