Performance - 64 Bit vs 32 Bit

[AQUAR]

For anyone using a PC with multiple cpu cores (like an I7) and running a 64 bit windows 7/8 this might be of interest.

This forum has a thread that avidemux was maxing out cpu utilisation and that this causes overheating and damage.
Not so of course for properly functioning setups. But looking at my I7 based PC I noticed that cpu utilisation is actually really low for encoding with MPEG-4 ASP (xvid4). 

Part of the reason may be that 32 bit applications run under WoW64 (Windows on Windows).
It seems that under WoW64, the avidemux 32 bit - xvid4 encoder, runs on only 2 cpu cores. It stands to reason that it gets a bit of a performance hit (low cpu utilisation). Tweaking various settings for threading, cpu affinity etc makes no difference.
There is no such performance hit with the other encoders (maybe they call for better threading!).

Futhermore, by default windows 7/8 has core parking enabled.
On my PC the 64 bit avidemux runs mostly on 4 physical cores (I7 cpu) and barely touches the logical cores (they mostly stay parked).

Disabling core parking gives 64 bit avidemux a little bit of a performance boost again.

The upshot is that the 64 bit version can give more than three times the performance of the 32 bit version.
Cpu utilisation is up from about 16% with 32 bit to about 60% with 64 bit (no cpu parking).

Thats a good time saver for Xvid-HD recodes (on a 64 bit OS).

To change the core parking strategy you can do a registry tweak or use one of a few small utilites.
I use the free version of processlasso that has this "core parking" feature built in.

Don't know if there are tweaks to change WoW64 affinity for use with specific programs.