The most likely reasons for the difference are that the network slowness of a remote test drowns out small speed differences (you said C++ was 4 times as fast, but I bet the actual time difference is quite small), or that your remote host has a faster version of perl than your local machine (or a slower C++ compiler).

There is nearly always a performance advantage to writing things in C, but not a scalability one. Scalability has to do with being able to add more machines without changing your application.