Unity is a very high level engine, that uses C#, and it now has a system built in that lets you write code that looks like C# but will translate it to whatever SIMD instruction set is available, like ISPC.
There are also various libraries that leverage metaprogramming to do similar things. I don't think you understand what game devs are willing to do, to get a few more polygons and pixels on the screen!
> I don't think you understand what game devs are willing to do, to get a few more polygons and pixels on the screen!
Totally depends on the trade-offs. You can write your whole game in assembly, and target very specific hardware, and may be beat optimizing compiler (doubtful). But at what cost? Time spent on that could be spent on making more games.
Normal up to date hardware handles games just fine, as long as they are not using some abysmal and poorly parallelized engines. Modern CPUs with more cores are also helping that, especially after Ryzen processors opened the gates for it.
There are also various libraries that leverage metaprogramming to do similar things. I don't think you understand what game devs are willing to do, to get a few more polygons and pixels on the screen!