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Do you think that Windows Vista is too fast? Then Cpukiller 3 is the solution to your problem. It helps you to slow down your Windows machine easily. You think, I am kidding? Not really. There are indeed situations when you require artificial processor load.
One typical scenario is that you want to test an application that only shows certain problems if the CPU is under stress. Another typical problem is running a legacy application on a modern computer. Sometimes the old application will run so fast that you are not able to interact with it. Recently, I had such a problem with a new application. I used VMware Workstation on a powerful server, and I wasn’t able to access the BIOS setup of a virtual machine because the “press F2” message was only displayed for a fraction of a second.
Generating CPU load is not as easy as one might think. Of course, you could write a simple script that does the job. For example, a little program that generates random numbers in an endless loop is an option. If you don’t want to write a program yourself, you could use an application like Prime95, a tool for finding Mersenne prime numbers.
Other options are the free tools CPU Burn and CPU Load 2.0. The downside of these tools is that they don’t support multiple processor systems, i.e. they only stress one processor core. This problem can be solved by starting the tool multiple times and assigning the processor affinity via the Windows Task Manager. However, the main disadvantage is that you will only be able to generate a 100% CPU load this way. It might be hard to resume control over your computer, so be careful with these tools. It is probably not a good idea to run them on a productive server.
Cpukiller 3 is a bit smarter. It allows you to configure the processor load you want to generate. It also supports multiple processor cores. You can easily start and stop the resource occupancy via its GUI. The slow down factor can be set with its trackbar. It is also possible to configure hot keys, so you can control Cpukiller easily while you test your application.
Cpukiller 3 costs $29.50, which is a little too expensive in my opinion. I guess this is due to the fact that it has no real competitor. Please, let me know if you know of a cheaper, or even a free, tool that is comparable to Cpukiller. There is a trial which you can use for 30 days. Unfortunately, a trial session is limited to 20 minutes. You have to restart the program to begin a new trial session. So, if you find that Vista’s performance is really too good, then you have no other choice but to buy Cpukiller. 
Slow.exe on this page does the same thing for free. I’ve used it successfully for older games that run too fast on dual-core pc’s.
http://www.adrianboeing.com/tools.html
I always used to use something like the Distributed.Net client to burn in CPUs or test problems. It had a lot more tweaks then initially led on.
You can also ask directly VmWare to delay the boot at the bios level.
In the VMX file, add:
bios.bootDelay = 9999999
This software is interesting, but this vmware settings is good to know too!
I don’t know. I ran it on my XPSP3 laptop and slow down factor was 0%. I noticed no real slowness either.
I rate this a dud for the trialware and uselessness.
askew1, thanks! slow.exe is nice. It works on a dual core PC, but it can only strain one CPU core. So you have to run it twice and configure the CPU affinity if you require more than 50% CPU usage.
Jeremy, I think there are many way to stress a CPU. But sometimes you have to specify the exact slow down factor. This is where tools like Cpukiller come in.
Mathieu, thanks a lot for the tip. I already guessed that there is way to delay the boot process, but I didn’t find the solution fast enough. So I just removed the virtual disk temporarily.
Dave, hmm I didn’t try it on a XP SP3, but I see no reason why it shouldn’t work there. Did you log on as an administrator?
Thx This works a treat on Windows Server 2003 64 bit
JB