
Steve Reynolds, Internet Explorer program manager at Microsoft, explained that the problem centred on IE7's phishing filter.
When users attempt to open a web page with a large number of frames, the phishing filter causes the browser to take up unusually high amounts of processor power.
"This occurs when the phishing filter evaluates the page for each [frame] navigation, resulting in multiple simultaneous evaluations for each page," said Reynolds.
The update is currently available for all users. However, Reynolds said that only Windows Vista currently downloads the browser though the built-in Windows Update component. Other users will have to manually download the update from Microsoft.
Since IE7 was launched in October it has largely been the phishing filter's accuracy, not its processor use, which has come under fire.
A November study by Carnegie Melon University reported that IE7 failed to block more than 30 per cent of phishing sites tested.
In September a study funded by Microsoft reported that the browser blocked more phishing sites than Firefox 2.0, although Mozilla later issued a counter-study claiming that Firefox had superior phishing detection.