I just checked my AMD box and tailscale there can consume ~15% of cpu time when the tunnel is under active use. When it’s not used it’s ~1.5%. But it’s a low power old AMD cpu though (AMD G-T56N), so I’m not use if it compares to Ryzen 5. On my intel machine, it’s ~5% when under active use, and idle at ~0.5%.
As the CEO of a company that run several major social networks, he know the importance of privacy and choose to use a virtual background.