Speed Up Site Delivery With Subdomains

Stephen Yagielowicz

Adult websites tend to be fairly bloated affairs; laden with hi-resolution photographs, hi-definition videos and advanced scripting, that combined, can become a challenging and slow download across even the fastest Internet connections. Since no one wants to wait for a web page to load, webmasters are constantly seeking performance boosting options for speeding the delivery of their sites.

While this process may often involve costly redesigns and code optimizations along with investments in faster hardware and newer software solutions, there is a simple and often free-to-deploy technique that could nearly double your site’s perceived load speed: the use of subdomains to enable parallel downloads.

Subdomains are a simple and often free-to-deploy technique that could nearly double your site’s perceived load speed.

For example, most websites serve all files and content from a single domain, such as While this is acceptable, most web browsers limit downloads to two per web host — a legacy from prebroadband days. This means that a web browser will request two items from your website at a time, say the index page and CSS file. Then, it moves on to the next two items, such as a header image and background graphic; moving along until all of the requested page resources have been downloaded.

With many web pages containing more than 50 downloadable elements, the latency involved with the browser requesting and receiving an item and the server delivering and confirming everything, becomes the main source of download wait time.

By adding a subdomain,, from which your images are served, web browsers can simultaneously download that index and CSS file and the header and background images.

There is a practical limit to the efficacy of this interesting technique, however, with various studies showing the sweet spot to be two to four web hosts per page (after around four concurrent host requests, bandwidth and other limitations provide declining benefits) — and these web hosts do not need to be on separate servers — making the subdomain option an attractive one, which may cost only a few minutes in cPanel to deploy.

For instance, a domain map that included, images.example .com and, each serving the appropriate content, provides a significantly faster download time than will a single hostname solution, such as — and may cost nothing to implement and require modifications of only a few lines of code.