For example, Pratt said that if the same third-party advertisement appears 10 times on Web sites that a user is browsing in a session and the person's InPrivate Filtering threshold is set to 10, the user can then view how the third-party content owner is collecting information about browsing activities.

The Compatibility View introduced in IE8 beta 2 also got a refresh in RC1. The feature allows users to view Web sites that may not be compatible with current Web standards IE8 supports in another view so the sites render properly.

Microsoft added more support for current Web standards such as CSS (Cascading Style Sheets) and RSS in IE7, but sites that were designed for previous versions of IE that didn't support these standards didn't work properly. One of Microsoft's chief goals for IE8 is to make it as Web standards-compatible as possible, but also to ensure older sites can be viewed the way they were designed.

In IE8 RC1, Microsoft built into the browser a list of common Web sites that it discovered must be viewed in Compatibility View mode to render properly, Pratt said. Now when someone browses these sites in IE8 RC1, they automatically appear in that mode without a user having to click on a "Compatibility View" button, as they had to in IE8 beta 2, he said.

Microsoft also tweaked browser performance features so IE8 RC1 opens faster as an application and also opens new tabs or Web pages faster, the company said.