I doubt it is a real problem for anything other than number crunching. I like to use tcc during development (which does very little, if any optimizations) to speed up compilation and I never noticed any regressions in performance, even for GUI software. Throughput just isn't that big of a deal for most applications (although latency and resource usage is, but that's not affected by choice of compiler).
I used SDL2. Not actively working on that project anymore, but I picked it due to requirements - fast startup, low latency, low memory usage, portability anywhere (linux on multiple distros, CPU architectures and multiple rendering backends, any Windows version from XP to 11...). C fits that very well IMO and I don't regret choosing it.
