Ok heres something you could try. go download the binary from the following site:
http://www.animus-facticius.org/lame_dm/lame_dm_preset.zip

The presets are activated by "--dm-preset" followed by, "standard, xtreme, insane, metal"
Here is what the following presets specify:

Standard Preset = --nspsytune -V2 -mj -h --lowpass 19.5 -b112 --nssafejoint --athtype 4
--dm-highfreq 3

Xtreme Preset = --nspsytune -V2 -mj -h --lowpass 19.5 -b112 --nssafejoint --athtype 2
--dm-highfreq 3 -Y

Insane Preset = --nspsytune -V1 -mj -h --lowpass 19.5 -b112 --nssafejoint --athtype 2

I have been using the extreme preset and haven't had any problems so far. I have an amd duron running at 800mhz and i usually get 2x encoding speed. The nssafejoint switch is for a new more accurate joint stereo.

Sean