Hi T_Flight...yes you are right,there is a drop in speed.
I try to explain why! This is not a bench program,like most people think,it's a full working chess program with a high level engine.
Every programmer gives to there engine alot settings...to make it not complicated i have put these settings in advance in the program,so that it's
for every body same testing with same settings.

On every screen you see two values memory(i will take the screen here on this page above from vmsein as example)
1.Up in the middle you see 4096Mb = is his free memory the system have.
2.Under in Analyse window,just next the name TogaII142JD-8cpu you see 135Mb = Hash Tables = HT

What is HT = i have give the engine 135Mb HT is memory he use where he can put his calculatings he wants to keep!
every time he goes one Depth deeper,he can look in this memory(data) so that he has not to calculate the same line anymore that he already knows.
This goes on till this memory is full !! from that moment you get a drop in speed,because when he calculate further,find better lines,he has to remove
old data to make place for new better data!

Ofcourse you can give more HT to the engine so long you have free memory...if you have 6Gb...you can give 4Gb HT to the engine if you want...and the engine
can keep alot more data in his memory! and will go a little faster..till memory is full.

This is just a little test,because most people get use to test there system with known Benchmarks..like Pi..just a few seconds,and done..but with chess is it endless
you can continue hours,days,forever calculating till chess is calculate out!
So i have to make something small..that don't take long time,and acceptable for most testers.

I hope this simple explain is clear enough..because chess is much more then just caculatings!

Oh yes..chess is the most stressing game you can find,and we as chess players,don't like so much Vista,because it slow down the system,you get lower
calculating speed,so we stay with XP...some engines get even a gain from 60% speed if you run Win XP 64bit!!
But that's only for Xtreme people who want the max. performance!

JP.