I have a 19GB test file on a desktop Xeon e3-1230 v5 (a quad core Intel from 2015) and an encoder written in Go (not the fastest language).
I can turn a 19GB file into 10 2.4GB files in 44 seconds, I can recover the original with any 8 of the 10 files. That sounds pretty slow, but it is reading 19GB and writing 24GB. In fact when I watch with top it looks like it spends a good while reading in 19GB, spends 1-2 seconds running the Reed Solomon calculation on 4 cores, then spending a bunch of time writing out 10 2.4GB files.
So Reed Solomon is fine even on a 6 year old computer on a pretty large file. I suspect a current 8 core desktop from 2020 could do even a 100GB file without taking noticeably long. After all a 100GB file shared over a p2p network is going to take WAY longer than the reed solomon calculation. Similarly I expect a recent vintage android phone or IOS phone could manage similar not to differently than a 6 year old desktop.