just wondering this might be a dum but if you encode to xvid with virtualdub and it is a 2 pass.On 1st pass you set high motion estimation, vhq 4 but then on 2nd pass you take vhq to 1 and motion estimation dow to 1 it would boost your speed but not lower quality beacause the 1st pass did all the sats and motion estimation so it wouldnt matter because xvid is reading of the stats.

VHQ is disabled during 1st pass

I can still select it in 1st pass but probably does do it in 2nd pass.But what about motion search precision options.

keep them the same, in general it is not advisable to start changing your settings between the 2 passes.

MSP = 1 is really bad for quality in a bitrate/filesize based encoding, REALLY bad. Not only the settings during first pass count, the settings during the 2nd pass count more.

Encoding video is generally a lot slower than audio, live with it

How about the turbo option?
and don't use the GMC if you are hurry...

xvid does not save motion vectors from the first pass. Fast first pass doesn't use high quality motion estimation so the results would be useless for second pass.

Turbo is only for the second pass, and only affects Qpel and B-Vops. So if you have those disabled (not recommended), Turbo wont do anything. If you use Qpel and B-Vops Turbo will give you a nice speed boost tho, and most people cant notice the difference between Turbo Qpel and stardard Qpel.

Well, i tried mess setting between two pass:
First pass turn off all option, except some B-VOP settings(didn't turn off the Motion search precision, turn it off will be no P/B frames at result video...),
Then turn on all options at second pass.
Result is,
Messed setting between two pass, video size will be smaller than normal twopass setting.
Don't know why...

EDIT: It is hard to notice the difference between two video...

After done several test with XviD encoding speed,
i found it is no way to increase the encoding speed at first pass,
whatever option i turn off, or turn on,
unless resize the source video to smaller resolution or buy a faster computer.

Testing environment:
Pentium 4 2.4GHz
Intel 845GRG motherboard
512MB DDR266 SDRAM
Maxtor Diamond Max Plus 8 40GB 7200RPM (destination drive)
Maxtor Fireball 3 40GB 5400RPM (Source video in this drive)
Windows XP SP1
VirtualDubMOD with fast recompress mode
XviD 1.1.0 beta1 ICL 8.1
MPEG1 video clips 320x240/640x480, both of them contain around 4300 frames.

Encoding 320x240 video clip, time remaining is 29sec(can't get the exact fps because its variable).
640x480 is 1.29sec.

EDIT: see my post? last line with red color?
noone try to correct me
the actual value is 1min 29sec.
Sorry