Dell Inc., No. 4 in the Internet Retailer 2017 Top 1000, continues to improve on its already fast desktop home page.

The computer and electronics retailer moved up five spots to No. 6 on Internet Retailer’s May Desktop Performance Index. The May index monitored Internet Retailer’s Top 100 retailers’ desktop home pages between April 24-May 7, according to data provided by digital performance analytics company Catchpoint Systems Inc. Catchpoint provides Internet Retailer with two monthly site performance indexes, one for mobile sites and one for desktop sites.

Dell’s website loaded on average between April 24-May 7 in 1.61 seconds, which is 15% faster than when it loaded in 1.90 seconds for the April index, which monitored websites between March 27-April 9. The site loaded faster because Dell reconstructed page elements to download at the same time instead of consecutively, Catchpoint says.

“More importantly, several third-party services, including some used for tag management, are now arranged to load after more critical content, which has helped improve the user perception that the page has loaded and is ready for interaction,” a Catchpoint spokesman says.

Similarly, Best Buy Co Inc. (No. 10) cut its load time by 1.63 seconds to 5.48 seconds from 7.11 seconds the previous month. However, the retailer still sits near the bottom of the index at No. 90.

Best Buy cut its load time by reducing the time spent running Javascript and cascading style sheets (CSS) in the browser, Catchpoint says. “With more code execution work being assumed by the browser, reducing some of this workload can improve web page load times,” the spokesman says.

For the two weeks of April 24-May 7, the Top 100 retailers’ average load time was 3.57 seconds compared with 3.54 seconds the previous month. The 100 leading North American retail sites are those ranked by Internet Retailer by online sales in 2016, according to Internet Retailer’s Top500Guide.com.

The average page weight was 2.79 megabytes compared with 2.73 megabytes the previous month, and the average number of hosts was 48 compared with 47. The average number of items per page was 169 compared with 166 a month ago. The 100 sites were, on average, 99.87% available for April 24-May 7, compared with 99.94% available for March 27-April 9.

Catchpoint monitors each website’s home page with measurements taken from Catchpoint’s in-country or in-region monitoring nodes, 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 web page load time, availability, hosts and items.

They are defined as follows:

Web page 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 two-week 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 or Requests: Web page 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.