Just how much extra system resources does Vista Aero UI take?

Whenever anyone mentions the Windows Vista operating system, someone is bound to bring up the fact that Windows Vista is slow and takes up to much in the way of system resources and that is needs some sort of supercomputer to run.  This is plainly untrue and the people who are saying this are either misguided, mistaken or lying.  However, it is true is that you need more power to run the new Aero user interface.  But just how much extra power does this take? 

Let's see if we can find out.

Finding out the performance hit of the Aero UI (user interface) isn't as easy as it sounds.  First off, the Windows Vista device drivers are, how shall I put it, far from optimized.  Compare the gaming performance of two PCs that have identical hardware configuration but where one is running XP and the other is running Vista and XP beats it without a doubt.  I expect that it will take GPU makers several months to come out with truly optimized drivers for their boards and until then hardcore gamers are probably better off sticking with XP. 

Another problem is the unreliability of current benchmarking tools under Vista.  Many simply give up at the first hurdle and plain don't play nicely, while many of those that work seem unreliable and give wildly conflicting results.  Nothing that I have access to seemed reliable enough to quote.

So, what does that leave?  What about Windows’ own Task Manager?  It's not all that fancy but it does give a good view into what's going on.

My tests aren't very scientific and consist of seeing what the performance change is like when switching between the Aero UI and the Classic theme.  I chose to take two values - the CPU usage and physical memory usage, both a percentage value.

The difference is small, but it's there alright.  On my main Vista machine (which has a Windows Experience Index of 4.4) which is running Vista RC1 build 5600, I noticed that when I had the Aero UI theme loaded, the CPU usage hovered at around 3% and the physical memory usage at about 27%.  However, with the Classic theme loaded these values dropped to 1% and 24% respectively.  Not much, but there is a measurable performance hit. 

Note:  During these tests I had a couple of Notepad windows open along with the Windows Task Manager.

Interestingly, there's a visible drop is system demand when transparency is disabled for the Aero UI.  Here the CPU usage seemed to drop from around 3% to around 2% (it didn't seem to have any effect on the physical memory used - which is as I expected).

From this we can extrapolate some basic conclusions:

• On a high-end system, the performance hit of running with the Aero UI is close to negligible
• The lower the performance of the system, the greater the Aero effect will be (in other words, the less system resources you have available, the more you're going to feel it)
• It's easy to switch between Aero and Classic

The main drawback of Vista for those who can't or don't want to run the Aero UI is that the Classic interface looks awful.  I hope Microsoft remedies this in the final release.