OT: Flowers for the grave of MoM.

[Esben Mose Hansen]

As for execution speed, there are plenty of tests out there. I random one from google is here.

As for cross-platform and as long as you plan to distribute the executables, there are lot of choices, from C/C++ (with XP libraries) to Perl, Python and Ruby. A short breakdown:

C/C++: Nothing beats these beast for availbility of libraries; relatively hard to learn; unparalleled execution speed.

Perl/Python: The two by far most popular scripting Languages. Both offer excellent XP, large libraries, slow execution speed and fast development time. Python is "stricter" and more formal than Perl; otherwise the Languages are very similar in aim&spirit, so pick the one you like the most.

Ruby: Is relatively new. If you don't care about popularity and large libraries, this may be the ticket. It looks really, really cool but I have not yet had the pleasure.