BD Inconsistent performance, unacceptable CPU usage

[QUINTIX256]

I understand the minimum requirements (Intel Core Processor Family, AMD Athlon 64 X2 3800+ 2.0 GHz or higher) describe generic desktops, not laptops, but frankly the bulk of the decoding and rendering is, or at least should be, done by fixed function hardware in the GPU part of my APU. Yet process-explorer pegs WinDVD11 at 68%.

The bluray drive I salvaged came from a prior laptop that would not meet these minimum (again desktop CPU) requirements, and it ran beautifully on a far inferior Radeon 4200 chipset graphics. It usually plays blurays without hiccups when nothing else is running, but not since the forced update required to play Invictus has it ran properly. It may work fine for several minutes, but then it gets snagged every 10 seconds or so.

A generic ~600mhz MIPS processor with fixed function AVC/VC1 decoding & AACS decrypting hardware is all it takes to play bluray. Sharing a dual-core 1.4ghz processor with two integer ALU pipelines apiece even with the most demanding app running in the background should not be an issue, but now even after disabling TrendMicro (which seemed to help for a bit) it just will not run smoothly.

Bluray drive is MATSHITA BD-CMB UJ141ES