So I have a 300 Mb connection, although I think it's supposed to be 400 now, but since late last year I get half to 1/3 of that. I think I need someone to come out and look at it. There might be an issue with my modem again. Anyway, I usually download from Steam at 30 to 40 MB/sec. With MFSim through their launcher, I was getting about 2 MB/sec. So it took me, according to Steam, 15 hours to download. Also during the download the launcher was using 50% CPU and 50% GPU (I7-6700K / RTX 2080 Ti). Kind of ridiculous.
BTW, I hear some are having issues with XBox One controllers that are bluetooth. I use the old one that required the dongle that's not bluetooth and it works perfectly. Normally I use a stick but I wanted to see what a controller is like and it worked well, other than being insanely sensitive by default. So if you want to use a XBone controller, try getting the old one with the dongle.