Zen Kernel is the opposite of "optimized for gaming".

It was once the default kernel for out-of-the-box gaming simply because it had fsync patches integrated. But since fsync is in the normal kernel for quite some time now zen is obsolete for that purpose.

I mean it's still an okay choice for any desktop environment but it is definitely not optimized for gaming as it sacrifices throughput and is more tailored to multitasking of a lot of smaller things running to provide a snappy desktop experience.