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Time to Interact and 3 Other Simple Definitions of Site Speed Performance

Brooke Seldin • June 27, 2016

You’re familiar with page load—also known as load speed, page speed, or time to load—as a way to measure eCommerce site speed, but what about time to first byte and time to interact? What do they mean and how do they affect site performance?

Here are four simple explanations:

Time to First Bye (TTTB)

Time to first byte measures how responsive a web server is. After a browser requests web page content, TTTB measures the time it takes a server to download the content and send it back to the browser.

The faster your server responds, the faster your pages will render and load. This reduces the time shoppers have to wait for your site to load, which in turn lessens the chance they’ll abandon your site out of impatience or frustration. For this reason, TTTB is a key indicator of site performance because of its impact on user experience, conversions, site abandonment, and even search ranking.

If your site experiences slow TTTB, a number of culprits could be to blame. Heavy web traffic, inadequate hosting, and a high number of page resources all contribute to slow TTTB.

Time to Start Render (TTSR)

Time to start render measures how long it takes for the first piece of visual content to appear on a browser screen after a user clicks a page element.

When a shopper clicks a button or link on your website, TTSR measures the time it takes for him to see the first visible result. That result could be your navigation bar or brand logo visible against a white background while everything else on the page has yet to load.

Reducing the time it takes for a shopper to see visible results improves user experience, and TTSR plays a key role in this.

Time to Interact (TTI)

Time to interact is the point when a user can interact with a web page element once the page has rendered. After a shopper clicks on the add-to-cart button, for example, TTI measures the time it takes for the an interactive element on the next page to become usable, such as the checkout button.

TTI is notable (pdf) because it’s the potential moment when a call-to-action button becomes usable by a web visitor. Rather than total load time, TTI is a better indicator of overall site performance because it directly affects user experience. The faster a shopper can interact with your site, the greater potential you have to increase conversion rates and sales.

Total Load Time (TLT)

Total load time measures how long it takes the browser to process and download all content on a web page. TLT has long been considered the most important indicator of site performance.

While reducing TLT can improve conversion rates, TLT doesn’t always indicate what the customer actually experiences and whether that experience is quality. For example, imagine two eCommerce websites that have identical TLT. If one of the sites has faster TTI, and therefore displays content faster, its potential for conversion increases faster than the other website’s.

Luckily there’s plenty you can do to improve time to interact and other site performance indicators. Check out our post on the Four Bulletproof Ways to Improve Your eCommerce Site Speed for a few quick-and-dirty tips.

Brooke Seldin is a marketing content specialist in LYONSCG’s Chicago office. She is a writer, an editor, and a content strategist who specializes in eCommerce, technology, and digital marketing for B2C and B2B organizations. She can be reached at

Brooke Seldin

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Brooke Seldin

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