I'm a total tech noob so it's maybe stupid but I was just also wondering about the proof-of-work thing as I recognized that my pc really needs to do a lot of work with the iota wallet so how does that work for every machine?
Current proof-of-work is set to very high difficulty to prevent spam attack, for IoT-friendly variant of PoW check "Network-bound" on
https://en.wikipedia.org/wiki/Proof-of-work_system#Variants.