According to Akamai's most recent State of the Internet Report, South Korea boasts the highest average internet connection speed in the world. Korea's internet users surfed at an average speed of 24.6 Mbps in the second quarter of 2014 according to Akamai's measurements (click here for details on their methodology).
Korea is trailed by Hong Kong, Switzerland and Japan who each saw average speeds around 15 Mbps. The United States ranked 14th with an average connection speed of 11.4 Mbps, which is still way above the global average of 4.6 Mbps. To add a little perspective on what these speeds mean: At 10 Mbps it takes around 50 minutes to download a 2-hour movie in HD quality.