Impact of slow page load time on website performance

Viki Green
3 min readJan 24, 2016

Website performance, underpinned by the user experience, is affected by a wide range of factors from page layout, to interface design, calls to action, and on page content.

Site and page load speed is another highly important factor and if not considered and optimised accordingly. Research has shown that a page load speed can impact heavily on search engine optimisation, engagement, brand advocacy and conversion levels.

The real cost

Impact on user attitude and behaviour

  • 47% expect a page to load in 2 seconds of less. 4
  • 40% of users will abandon a webpage if it takes more than 3 seconds to load. 4
  • A 1 second delay (or 3 seconds of waiting) decreases customer satisfaction by 16%. 4
  • 79% of shoppers who are a dissatisfied with website performance are less likely to buy from same site again. 4, 5
  • 52% of online shoppers state that quick page loading is important to their site loyalty. 4, 5

Impact on Revenue / Sales

  • If an e-commerce site is making $100,000 per day, a 1 second page delay could potentially cost you $2.5 million in lost sales every year. 7
  • 1 second of load lag time would cost Amazon $1.6 billion in sales per year” 1

Impact on Conversion

  • Optimal conversion is achieved at 2 seconds 7
  • 1-second delay in page response can result in 7% reduction in conversion3
  • 4-second page takes more than a -40% hit.8
  • 6-second page takes a -50% hit.8

Impact on Page Abandonment

  • Slow page load time dramatically increases page abandonment rate 7
  • 4-second delay in page response results in 25% abandonment rate 3
  • 10-second delay will often make users leave a site immediately. 7

Case Study: Walmart

Walmart’s Conversion Problem:

  • Walmart saw a sharp decline in conversion rate as average site load tie increases 1 to 4 seconds3
  • Overall average site load time was lower for converted population (3.22 seconds than non-converted population 6.03 seconds.) 3

Improvements & Results:

  • For every 1 second of improvement they experienced up to a 2% increase in conversions. 3
  • For every 100 ms of improvement, they grew incremental revenue by up to 1%. 3
  • Walmart also noted significant SEO benefits for entry pages and reduced bounces 9

Article References












Viki Green

User Experience Researcher | Travel | Outdoor Adventure