nVidia 8800 GT with Intel Q6600 Quad core.
Foobar 1.03 transcoding FLAC to FLAC (Pink Floyd Final Cut [13 tracks])
*** FLAC 1.2.1 @ 4 threads ***
level 8
Total encoding time: 0:22.277, 124.90x realtime
*** FlaCuda 0.91 ***
-8 - -o %d --verify
Total encoding time: 1:01.184, 45.47x realtime
-8 --cpu-threads 2 - -o %d --verify
Total encoding time: 0:50.529, 55.06x realtime
-8 --cpu-threads 3 - -o %d --verify
Total encoding time: 0:42.807, 65.00x realtime
-8 --cpu-threads 3 - -o %d
Total encoding time: 0:42.011, 66.23x realtime
-8 --cpu-threads 4 - -o %d --verify
Total encoding time: 0:42.027, 66.20x realtime
-8 --cpu-threads 4 - -o %d
Total encoding time: 0:41.356, 67.28x realtime
-8 --slow-gpu --cpu-threads 4 - -o %d --verify
Total encoding time: 0:37.939, 73.34x realtime
CPU usage with FlaCuda never peaks above 25% per core. Seems for a practical scenario with a quad core CPU it doesn't compete.