I have been using Avidemux to encode edited video using x264 and the mp4 container for most of my videos. My PCs are not new, using single-core AMD Athlon processors.

In 9.04 and 9.10 (Linux Mint), encoding speeds ranged from 7 to 10 frames per second. In 10.04 these dropped down to less than 2 frames per second.

I booted back into Linux Mint 8 (9.10) and the same video encoded at the previous 7 to 10 fps.

I tried with other videos in different formats (mpeg2 and VOB). The results were the same - 10.04 was extremely slow encoding x264 but Mint 8 was "normal" at 7 to 10 fps.

With a dual-core notebook, however, the encoding speeds ran at 8 to 14 fps in 10.04.

Anyone had the same problem? Was 10.04 optimized for dual and multi-core at the expense of single-core? If so, is there a way to restore "single-core optimization"?

Thanks in advance for any suggestions or ideas.