Hi fruhwirth,

i don't know what kind of libGL.so.1.2 you are using, it could even be an unaccelerated version of a MESA openGL driver.
If you have an ATI graphics card like i do (Radeon PRO), try taking the libGL.so.1.2 from version 8.27.10.
if you don't have the package at hand, download just that file from here. Don't forget to rename it to libGL.so.1 or create a symlink in your GE directory.
i am using this libGL.so.1.2, GE version 4.0.2414 in a 32-bit chroot'ed environment on a debian sid (unstable) AMD64 box, and have no complaints at all with the performance.
Concerning your question who will fix this issue i would think that both, ATI and GE would be able to fix this issue. I think it is more probable that GE fixes it but who knows.

Julio