We can debate the performance of a hypothetical compiler for eternity, or we can cite examples; slow compilers written in a non-C language along with publicly available input data.

i.e. benchmarks or it didn't happen.

Man, you are being difficult. Ruby is well known to be a very slow language (if you want numbers check http://shootout.alioth.debian.org/u32q/benchmark.php?test=al...). Optimizing compilers are computationally demanding tasks, and the proof (albeit extreme one) is Stalin Scheme compiler, that can take minutes to compile code, but the result is sometimes faster than C/C++ code, or at least on par. Now, this compiler is written either in Scheme itself or in C i do not remember, but definetelt not in ruby. If it take to compile your code a minute for a compiler written in [C/Stalin Scheme] it will take at least ten minutes for one written in ruby.

And I do not know where you saw me saying C is the ultimate language for making compilers. I never said that, I do not think so, I just said python/ruby are bad for the task.

Sorry, I must have misunderstood your intent then. Python and Ruby are probably fast enough for compiler construction as well; I am sure they could be tweaked by an expert to yield acceptable performance, but I am just not such expert :-)