The secret of Houdini chess engine is that it uses all the physical memory of your computer.It's not a chess engine as the other ones but a speedhack engine.Simply when you open task manager you see houdini is running.But you don't see that houdini is running in high priority.This is the internal Houdini hack.Make an experiment.Try to arrange an engine match between Critter 1.4a and Houdini 2.0C on Arena interface for example.Before starting the match,go to your task manager and switch Critter to high Priority.Then start the match.Critter is superior in speed too and manages to beat Houdini with a narrow margin
Houdini exploits your hardware to the very maximum of its abilities, more than most other engines. It's extremely well optimized to avoid idle time and to make the most of the CPU's potential. Depending on your system, this can translate into slightly higher CPU temperature or into a lower stable over-clock if your system is at the boundary of its over-clocking potential with other engines.
Concerning your crackpot theory about process priority, when Houdini is running you can simply check in the Windows Task Manager at what priority Houdini is running by right-clicking on the Houdini process. You'll find that it's running at the priority defined by the GUI, Houdini doesn't modify its process priority at all.
To avoid this problem when testing, I think it's simple : just test with same depth and not with a time control.
I just try a fast test on 100 games at 8 Ply depth for each engine ...
Better is to test with at least depth 20 but too much time necessary for this (I can only do these long test during the night).
Gui = Fritz 11
Book = HS 7 moves + (ctg)
Hash = 64mb
1 Critter 1.4 64-bit +40/-18/=42 61.00% 61.0/100 (+78 elo)
2 Houdini 2.0b Pro x64 +18/-40/=42 39.00% 39.0/100 (-78 elo)
And yes it seems very strange ... but need more games and more depth to conclude anything ... If someone can test it ...