but if you come from C++ you might be disappointed by the performance,

That's true, but probably not to the extent you imagine. The OpenGL module has "comparable" performance to C, according to these benchmarks: http://graphcomp.com/opengl/index.cgi?v=0111s3B1&r=s3m3.

I second the comments about Tk and Wx. You might also like to look at GtkPerl (it's cross-platform).