Let's try to clear up some confusion here:
The original bug that was reported in this thread ("GF100 VDPAU performance is really not good") was reproduced at NVIDIA using the same hardware (HP EliteBook 8740w) as the original reporter (camelreef). After some investigation, it was determined that the reason PowerMizer was unable to enter the highest performance level was because of an interaction between the DSDT in HP's BIOS and the Linux kernel's ACPI subsystem; in fact, the exact same issue which is responsible for a blank screen on EliteBook 8x40w systems that have the optional DreamColor eDP panel installed .
camelreef, sorry for not communicating this back to you sooner. The thread about the blank screen issue contains details on how to patch your DSDT to enable correct functionality. HP sampled us a BIOS with which we were able to verify that both issues (the blank screen and the low performance) were resolved, but it appears that they have not yet made a public release containing the needed changes.
For those of you who are experiencing similar issues on other systems than HP 8x40w series notebooks: if you are using a notebook system or other system with the GPU on an MXM, please check your DSDT for an issue similar to what is described in the thread about the blank screens. If you discover a similar issue, please check to see if patching your DSDT resolves it. (Note: on the HP 8x40w notebooks it is sufficient to change the order of the two device definitions; on others, this may not be possible, and the workaround may not be as trivial.)
If you are on a non-MXM system, or an MXM system without aliased device definitions or on which a patched DSDT does not resolve your issue, please start a separate thread and include details sufficient to reproduce your reported problem. (See the stickies on this forum.)