I love tailscale, but the performance overhead on file transfer (my primary use case for it) is very real. Samba transfers take a 15 megabyte per second hit over tailscale even with a fairly fast CPU on both ends (Ryzen 3600 and Ryzen 7900X3D) on my local network
15 MiB/s is trivially handled by any CPU you're likely to run. Indeed 100 MiB/s seems reasonable. 15 MiB/s cap seems either the protocol being used is doing too many round trips (assuming the machines you're testing with are far apart) or the network that's being set up requires routing through Tailscale's infra for hole punching.
These are on my local network, connected to my switch over 1gig Ethernet.