Repeating any single string several times looks bad (and might be bad for other reasons), but should not lead to a performance hit. Consider the fact that each of these occurrences that you see is just a pointer to the single string that was created when the code was read in.
I was wondering, about the delay during the initial interpretation of (load "arc.arc") and (load "libs.arc") everytime arc is invoked : is that possible to load (and eval) these files once in mzscheme and then save the whole memory in an executable, à la SBCL (maybe other CLs, too) ? I couldn't find it in mzc's doc or in mzscheme's functions, at least in the older versions. That will not solve the problems after loading, I guess, but this one is quite boring (I find).
