Curious to know the coolest things you achieved by configuring your kernel. I know kernel config can be boring, but I'm hoping someone will have an impressive answer.
For me I have a very lightweight kernel that runs wayland on nvidia without any issues to date.
The first time I configured the kernel was in Gentoo. The gain from the configuration it self may not have been much, but making my own initramfs image to bundle and load with the kernel taught me a bunch of how linux works in early boot.