No, really, wireguard encryption overhead is negligible unless you have a really old CPU (like a Pentium100 or something).

Whatever slows down your N100 is not wireguard per se, probably some tailscale overhead going trough their servers.

I have a fairly dated rented server, with an Atom D510, 2 cores, which is 10 years old, and accessing it over wireguard or not, I can still max out the network bandwidth without any visible CPU overhead.