Your 32-bit 3.99 compiles are interesting. The NASM compile is actually faster than the Rarewares 3.98.4 version. What does "NASM" mean in this case?
NASM compile uses "Netwide Assembler" code for some routines. Btw., using the very same VC9 and compiling 3.99 and 3.98.4 (ReleaseNASM configuration), there is not much of an speed difference:
LAME 3.98.4 32bits (http://www.mp3dev.org/)
CPU features: MMX (ASM used), 3DNow! (ASM used), SSE (ASM used), SSE2
Using polyphase lowpass filter, transition band: 18671 Hz - 19205 Hz
Encoding w:\cd\Prince\1988-Lovesexy\01 Songs are in a continous sequence.wav
to x.mp3
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=2)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
103492/103492(100%)| 2:22/ 2:22| 2:22/ 2:22| 18.913x| 0:00
32 [ 0]
40 [ 1] %
48 [ 0]
56 [ 1] %
64 [ 0]
80 [ 4] *
96 [ 115] *
112 [ 1580] %**
128 [ 7331] %************
160 [ 40039] %%%***************************************************************
192 [ 33304] %%%%%%%%%%%********************************************
224 [ 11836] %%%%%***************
256 [ 5489] %%********
320 [ 3792] %%*****
-------------------------------------------------------------------------------
kbps LR MS % long switch short %
185.5 12.5 87.5 88.0 6.4 5.6
Writing LAME Tag...done
LAME 3.99 32bits (http://lame.sf.net)
CPU features: MMX (ASM used), 3DNow! (ASM used), SSE (ASM used), SSE2
Using polyphase lowpass filter, transition band: 18671 Hz - 19205 Hz
Encoding w:\cd\Prince\1988-Lovesexy\01 Songs are in a continous sequence.wav
to x.mp3
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=2)
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
103492/103492(100%)| 2:20/ 2:20| 2:20/ 2:20| 19.266x| 0:00
32 [ 1] %
40 [ 0]
48 [ 0]
56 [ 0]
64 [ 0]
80 [ 0]
96 [ 2] %
112 [ 81] %
128 [ 5400] %********
160 [ 43295] %%%%%%************************************************************
192 [ 37019] %%%%%%%%%%%%%%%%%****************************************
224 [ 8887] %%%%%*********
256 [ 6608] %%%********
320 [ 2199] %%**
-------------------------------------------------------------------------------
kbps LR MS % long switch short %
184.8 19.1 80.9 88.0 6.4 5.6
Writing LAME Tag...done
LAME 3.98.4 32bits (http://www.mp3dev.org/)
CPU features: MMX (ASM used), 3DNow! (ASM used), SSE (ASM used), SSE2
Using polyphase lowpass filter, transition band: 16538 Hz - 17071 Hz
Encoding w:\cd\Prince\1988-Lovesexy\01 Songs are in a continous sequence.wav
to x.mp3
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III (11x) 128 kbps qval=3
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
103492/103492(100%)| 3:17/ 3:17| 3:17/ 3:17| 13.677x| 0:00
-------------------------------------------------------------------------------
kbps LR MS % long switch short %
128.0 7.8 92.2 92.9 4.1 2.9
Writing LAME Tag...done
LAME 3.99 32bits (http://lame.sf.net)
CPU features: MMX (ASM used), 3DNow! (ASM used), SSE (ASM used), SSE2
Using polyphase lowpass filter, transition band: 16538 Hz - 17071 Hz
Encoding w:\cd\Prince\1988-Lovesexy\01 Songs are in a continous sequence.wav
to x.mp3
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III (11x) 128 kbps qval=3
Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
103492/103492(100%)| 2:58/ 2:58| 2:58/ 2:58| 15.177x| 0:00
-------------------------------------------------------------------------------
kbps LR MS % long switch short %
128.0 8.5 91.5 92.6 4.1 3.3
Writing LAME Tag...done