I was using partial evaluation a little more broadly than you, and I understood you the first time :)
You're right that profiling isn't widely used on Linux yet, mostly, I believe, due to inertia. However, the Firefox build for Windows is compiled with the benefit of profiling data. It's not compiled with profiling on Linux only because Mozilla doesn't think it's worth the engineering effort to make it work with GCC. If you had profiling data, you could do algorithm specialization (which is really just a special case of partial evaluation IMHO) very easily.
Also, bear in mind that this is just one, small performance optimization. C++ beats Java with respect to many others.