If you're wondering why devs still can't reproduce this issue - it's because they're testing on a PC with an Intel CPU.
The OP also has an AMD CPU and what's even more interesting, it's of the same K10h architecture.
These CPUs are very sensitive when it comes to memory transfer performance from/ to CPU/GPU (they're significantly slower in this area compared to Intel's CPUs).
Coherent mapping removes *a lot* of that overhead and makes these CPUs much more efficient with the OpenGL backend.
The OP also has an AMD CPU and what's even more interesting, it's of the same K10h architecture.
These CPUs are very sensitive when it comes to memory transfer performance from/ to CPU/GPU (they're significantly slower in this area compared to Intel's CPUs).
Coherent mapping removes *a lot* of that overhead and makes these CPUs much more efficient with the OpenGL backend.