That reason is not performance but familiarity and ecosystem.
A trendy way in gaming to build games is to use ECS which is FP and there are very performant framework to do ECS.
I would argue (pretty hard) that the reason is actually performance.
The ecosystem matured around C-style procedural language concepts because naive functional implementations simply weren't fast enough (and were often much more difficult to work with).
Yes - some companies do leverage FP concepts for development, but they're usually heavily modified for that specific purpose (ex: GOAL at naughty dog, ECS for Unity)
And even then... ECS is "vaguely" functional at best. The entities are mutable, and the logic in the systems is directly modifying those mutable entities. I appreciate that the logic is applied consistently, and I think there's value there that comes from FP - but it's very much not classic FP.
The ecosystem matured around C-style procedural language concepts because naive functional implementations simply weren't fast enough (and were often much more difficult to work with).
Yes - some companies do leverage FP concepts for development, but they're usually heavily modified for that specific purpose (ex: GOAL at naughty dog, ECS for Unity)
And even then... ECS is "vaguely" functional at best. The entities are mutable, and the logic in the systems is directly modifying those mutable entities. I appreciate that the logic is applied consistently, and I think there's value there that comes from FP - but it's very much not classic FP.