One ISP in Japan improved its speed more than any other ISP for the month of September on the Netflix ISP Speed Index , a monthly update on which ISPs provide the best prime time Netflix streaming experience.

SoftBank-DSL in Japan saw an increase of .4 Mbps (megabits per second) to 3.2 Mbps, an improvement over its last two months of 2.8 Mbps performance. Overall, Japan’s country speed average stayed steady at 3.4 Mbps in September.

Eight ISPs saw a decrease from August’s numbers with .2 Mbps drops, including ASINetwork in Honduras at 2.2 Mbps, MTNL in India at 2.6 Mbps, Viettel in Vietnam at 3.2 Mbps, DIRECTV in Colombia at 2 Mbps, Optix at 2.6 Mbps in Pakistan, PakistanTelecom at 2.4 Mbps in Pakistan, Qualitynet at 2.8 Mbps in Kuwait and TELE2 DSL at 2.8 Mbps in Sweden.

A recent addition to the Netflix ISP Speed Index, Australia’s Foxtel, registered 3.6 Mbps for September. Australia’s overall country speed improved to 3.6 Mbps for the month, up from 3.4 Mbps in August and July, the streamer said while detailing the ISPs’ speeds.

Twenty countries were in the top performance tier for September with an average speed of 3.6 Mbps, which included Australia, Belgium, Canada, Hong Kong, Hungry, Iceland, Israel, Luxembourg, Netherlands, Norway, Portugal, Romania, Singapore, South Korea, Spain, Sweden, Switzerland, Thailand, United Kingdom and the United States.

One country, Vietnam, saw an overall decrease in speed in September with a .2 Mbps decline to down to 3.2 Mbps.

The Netflix ISP Speed Index is a measure of prime time Netflix performance on a particular ISP and not a measure of overall performance for other services or data that may travel across the specific ISP network.

Faster Netflix performance generally means better picture quality, quicker start times and fewer interruptions.