FWIW, I've done some pretty complex part simulations in F360, and it's not that slow, on my Vega MacBook pro 2018. But, if it is, Fusion has online-sim calculator or renderers that are pretty affordable.
Probably has to do with other software like Maya or other simulation like programs. In fact F360 worked flawlessly on my 2016 dual-core 2.0 ghz CPU with 8gm of RAM.