"Running IPv6 affects the performance of my servers, making it up to 30% slower."

The argument comes from a publication from Gartner (138557). However, the reasoning behind it is not given, and we find this performance difference very unlikely when IPv4 and IPv6 are handled by the router in the same way. Anyway, an organization must always test whether the IPv6 performance of their servers meets the standard set by IPv4. If not, the servers may need to be upgraded or replaced.