Netflix has released its March rankings of ISP streaming video performance. According to this latest update, Verizon FiOS still tops all large ISPs with an average delivery of 3.79 mbps. Things change if you expand the list to include smaller ISPs, where Midcontinent, Grande Communications and Wide Open West all beat FiOS with scores of 3.82, 3.82, and 3.81 mbps, respectively. Netflix says some encoding tweaks made to its compression algorithims notably impacted the rankings last month.
“If you look at the US ISP Speed Index graph, you ll see the group of top performers started moving collectively down last month and again this month,” Netflix notes. “That movement as a group reflects more efficient streaming on those networks due to our encoding work.”
Netflix uses the first episode of House of Cards Season 4 as an example of the shift. That episode has been streaming at 720p — starting at 910 Kilobits per second (Kbps) — and 1080p starting at 1620 kbps. Netflix notes that the lowest bit rates for those same streams were 2350 Kbps and 4300 Kbps, respectively.
This month Netflix also took some extra time to single out CenturyLink as a notably awful performer in its index.
“In the US, CenturyLink, whose performance has steadily slid since last November, now ranks last in the index with an average monthly speed of 1.53 Mbps,” the company said in a blog post. “By comparison, the slowest country we currently track — Costa Rica — posted average monthly performance of 1.87 Mbps in March.”
Note that by and large end consumers won’t notice much of an actual difference between the top five broadband providers on the list, where a fraction of a megabit per second can separate companies. Performance can also vary depending on whether an ISP has joined Netflix’s Open Connect Content Delivery Network, or if they’ve struck a direct interconnection deal with Netflix.