So your concern for any compiler is all about the theoretical possibility to improve the compiler's performance in producing performant binaries. In my opinion, I am completely unconcerned for this. I believe in my ability to calculate run time and run space processing with big O notation. I believe in my ability to divide computations with multi-threading-multi-processing technology. I believe in not wasting my programmer resources into premature optimization.
I appreciate that there are plenty of software applications in which tight computer resource accounting can translate into serious business cost savings. I don't know your situation, but I've never worked on any development project that had that kind of constraint.
tl;dr I really don't care that GNU's C compiler can produce a faster fizzbuzz than SBCL does