Making broad claims like this without a source or links to benchmarks feels like FUD to me. For example Tailscale's comparison page on performance (https://tailscale.com/kb/1148/tailscale-vs-nebula/#performan...) doesn't mention a meaningful performance difference, so if you're claiming they're not telling the truth (by omission), I'd hope to see more to that than just a straight assertion, even just "We tried Tailscale in Slack's network and it wasn't able to keep up with our usage patterns".