High CPU usage in Microsoft Edge can occur when multiple web pages are open, particularly if those pages contain active graphics, ads, or background processes. Each page can contribute approximately 2.5% to CPU usage, leading to significant overall consumption when many tabs are open. The nature of the websites plays a crucial role; some sites with heavy graphics or continuous data updates can cause CPU spikes. Ad-blockers can help reduce CPU load, as ads often contribute to higher usage. Additionally, certain websites may be optimized for specific browsers, leading to performance issues in others. Malware or tracking software can also impact CPU performance, highlighting the importance of regular scans and using effective antivirus solutions. Overall, managing the number of open tabs and being mindful of the websites visited can help mitigate excessive CPU usage.