Running one or several Flash ads that use a lot of processing power on the same page view will degrade the user experience significantly.
To help detect these ads we have added monitoring of CPU usage in Advalidation. To get results that are as realistic as possible all creatives are tested in Internet Explorer 7 on virtual machines running Windows XP.
Below is a screenshot of how we display the CPU usage of Flash ads in Advalidation. This ad clearly uses too much processing power and would slow down the web site significantly.
In your validation settings you can choose from three levels. Tolerant, moderate or strict.