https://devblogs.microsoft.com/aspnet/grpc-performance-impro...
That GC in particular has to stop the world, traverse the entire fresh heap, guesses whether something is even a pointer (and can guess wrong, causing a memory leak!), and does all this at arbitrary times, unless you do non-idiomatic things like manage your own memory in preallocated arrays, or use C/asm-powered memory mapped buffers [0].
Nothing comes for free, and some domains can't pay the price for GC (and choose to spend those resources elsewhere). Games, in my opinion, are largely still in that category.
I wonder what exactly makes code "idiomatic" in a GC language. It is one of the greatest misconceptions about GC languages that you shouldn't worry about allocations at all. For me, GC mostly means the correctness guarantees which come with it and the convenience, that I don't have to track every single allocation and mange it manually. However, it still means that I should be aware of all the larger allocations and avoid them as in any other language, if I am looking for performance. Not reusing allocated memory where reasonable is detrimental to the performance in any language. And of course, the choice of the right GC approach can also help with applications like games. Lispworks even provided a Lisp environment for a Nasa probe, the GC had real-time capabilities.
https://docs.unrealengine.com/en-US/ProgrammingAndScripting/...
Just because a language has a GC doesn't mean one needs to use it 100% of the time, which is exactly what is behind the .NET 5 performance improvements that top C++.
By making use of stack allocations, value types, memory slices, native heap allocations.
Features that Common Lisp also supports, and I bet Allegro and LispWorks are better than SBCL in the performance chapter.
