I tried using Syncthing to backup my two kids Windows 10 laptops C:\Users\user folders to a home machine but found, it was always chewing CPU in bursts and making the fans whir.

I tried adding ignores for parts we didn't care about so much and fiddling with various settings, but it was still quite problematic.

Although I would prefer an open source solution, I'm looking at trying Resilio Sync next.