I'm not sure what performance improvements you're talking about. As far as I'm aware, the difference between distros on performance is extremely minimal. What does matter is how up to date the DE is in the distribution provided package. For example, I wanted some nvidia+Wayland improvements that were only in kwin 6.1, and so I switched from kubuntu to neon in order to get them (and also definitely sacrificed some stability since more broken packages/combinations get pushed to users than in base ubuntu). It's also possible that the kernel version might matter in some cases, but I haven't run into this personally.
I think the main differences between distros is how apps are packaged and the defaults provided, and if you're most comfortable with apt based systems, I'm not sure what benefit there's going to be to switching (other than the joy in tinkering and learning something new, which can be fun in its own right).
For some users less experienced with linux, the initial effort required to setup Ubuntu for gaming (installing graphics drivers/possibly setting kernel options, etc) might push someone toward a distribution that removes that barrier, but the end state is going to be basically identical to whatever you've setup yourself.
The choice between distributions is probably more 'what do I want the process to getting to my desired end state to be like' and less 'how do I want the computer to run'.