LAME 3.13 timings from  Alex Nemirovsky.
 

WAV file:   284 second
 

266 Mhz Pentium, 66 Mhz FSB, 512 KB cache at 66Mhz   encoding time:       295 sec,

233 Mhz Pentium II/ 66Mhz FSB, 512 KB cache at 115Mhz encoding time:     234 sec,

200 Mhz Pentium Pro/66Mhz FSB, 256KB cache at 200Mhz encoding time:    257 sec,

300 Mhz Celeron 300A/66Mhz FSB, 128KB cache at 300Mhz encoding time: 180 sec,

300 Mhz Pentium II/66Mhz FSB, 512 KB cache at 150Mhz, encoding time:     176sec,