Processor: 2x Intel Xeon E5502 1.87GHz
Memory: 8 GB
OS: Ubuntu 8.10

Codec: mp4/h264
Bitrate: 1000 kbit/s

The results below are an average of 20 ffmpeg 2-pass runs for both 3 threads and 7 threads. The first file is a small one, 4.5 MB, the second file is 1.0 GB. The average durations are shown in the format mm:ss.

File 1

Duration: 29.88 s
Size: 4.5 MB
Total time reduced by: 30.4%

pass 1 pass 2 total
3 threads 00:08.78 00:36.3 00:45.1
7 threads 00:06.1 00:25.3 00:31.4

File 2

Duration: 1452.60 s (24 min, 12.6 sec)
Size: 1.0 GB
Total time reduced by: 37.6%

pass 1 pass 2 total
3 threads 04:10.5 32:31.9 36:42.4
7 threads 02:38.8 20:14.7 22:53.5