Slow speeds in Windows 8 may be due to the poisoned DNS cache that may contain invalid or expired DNS records. In case the DNS cache gets poisoned, technically known as 'DNS spoofing,' or the IP address of the web server changes, users may face difficulties opening the websites, or sometimes may also get HTTP error messages. In such cases, users are required to clear the DNS cache by flushing the invalid or expired DNS entries. After flushing the DNS cache, the new IP address of the website is then automatically resolved by the DNS client, aka DNS resolver, with the help of its authoritative DNS server. Users should also delete the temporary files stored in the %Temp% folder, which also helps expedite the Internet speed in Windows 8.