Instructions
Stop any downloads occurring on your Xbox. For example, if you're downloading the latest "Call of Duty" demo, pause it to finish after you are done using Netflix.
Turn off all other computers or video game consoles that are connected to the Internet while using Netflix. Even if your Netflix is playing through the Xbox, any other device using the Internet will use the same bandwidth. You can keep these devices on, but make sure nothing is downloading and unnecessary programs are running on the Internet.
Upgrade your Internet. Contact your provider to see if a better Internet is available with higher download rates and larger bandwidth.