The North Face, APMEX Inc. and Amway Global are newcomers to the top 10 list on this month’s mobile site performance index, provided by digital performance analytics company Catchpoint Systems Inc.

The North Face, which is owned by VF Corp., No. 92 in the Internet Retailer 2016 Top 500 Guide, jumped 16 spots to No. 5 on the October index, which is based on mobile site data for the two weeks Sept. 26-Oct. 9. APMEX (No. 42 in the Top 500) jumped eight spots to No. 6, as did Amway (No. 43) to No. 7.

These three retailers bumped Sweetwater.com (No. 89) further down the list to No. 9, while  Shop.com (No. 59) and Toys R Us Inc. (No. 35) were bumped off the top 10 list all together.

“The rise of North Face, APMEX and Amway this month is really the result of others, like Sweetwater and Toys R Us, losing a little steam,” a Catchpoint spokesman says.

The North Face reduced its mobile home page weight by 0.45 megabytes, which made its mobile site load time decrease by 0.41 seconds to load in 1.38 seconds. Meanwhile, APMEX and Amway each shaved only 0.1 and 0.2 seconds off their load times, according to Catchpoint.

“The performance differences among all these companies, for September and October, are pretty miniscule,” a Catchpoint spokesman says. “This shows how intense the battle for web performance is, and how shaving off just a few milliseconds of response time can really propel a company in the rankings.”

Internet Retailer and Catchpoint Systems produce two monthly site performance indexes, one for mobile sites and one for desktop sites, ranking the 10 fastest retailers out of the top 100 retailers in the Internet Retailer 2016 Top 500 Guide.

Catchpoint Systems monitors each mobile website’s home page with measurements taken from Catchpoint Systems’ 3G and 4G backbone monitoring nodes across the U.S., at intervals of five minutes for two weeks each month. Backbone monitoring nodes are the locations of Catchpoint’s devices that are near data centers operated by the main Internet Service Providers that provide service to a city. The nodes simulate end-user contact with each website. Catchpoint monitors webpage load time, availability, hosts and items. They are defined as follows:

Webpage load time: The time it takes for enough page elements to load for a consumer to begin interacting with a page, such as searching, tapping or scrolling. From a consumer point of view, the time it takes for the progress bar or spinning wheel to stop.

Availability: The percentage of time during the test week that the site can be successfully reached by a consumer.

Host: Any domain that delivers data, content or services over the Internet to the site.

Items: Also known as requests. Webpage components, such as files or images that a page loads from internal and external hosts or domains. These can include PDFs, PNGs, JPEGs and GIFs.

The top 10 retailers are ranked based on their mobile home page load times on 3G and 4G networks.

For the two weeks Sept. 26-Oct. 9, the average load time for the top 100 retailers was 2.88 seconds, which is 0.11 seconds slower than the 2.77-second average for the first two weeks in September.

The average page weight was 1.90 megabytes compared with 1.87 megabytes last month, and the average number of hosts was 44 compared with 43 last month. The average number of items was 134 compared with 129 the previous month. The top 100 sites were, on average, 99.81% available for the first two weeks of October compared with 99.80% available last month.