The feature that protects against fraudulent Web sites, new in IE 7, in some cases could bog down computers running Windows, according to an article on Microsoft's support site published Tuesday. This could happen when a Web page contains many frames or when a user browses many frames in a short time, the company said.
"When you use Windows Internet Explorer 7 to visit a Web page, the computer may respond very slowly as the Phishing Filter evaluates Web page contents," according to Microsoft. "Internet Explorer 7 evaluates the whole Web page when you browse a frame. Therefore, CPU (central processing unit) usage may be very high."
IE 7, released in October, is the first major update to Microsoft's ubiquitous Web browser in five years. Security was the No. 1 concern for the update, Microsoft has said. The phishing protection has been a major focus for Microsoft, shielding against malicious Web sites designed to trick users into handing over their personal information.
Mozilla also offers phishing protection in Firefox 2. By default, the Firefox feature works with downloaded blacklists of known phishing sites. IE 7, by contrast, checks in with Microsoft to see if a site is known to be untrustworthy.
Microsoft made a fix available on Tuesday, the same day it released 7 security bulletins with patches for 11 vulnerabilities in various products. The phishing fix was not pushed out alongside the security updates but is available on Microsoft's Web site.
