Loading times that are “excruciatingly” slow and unwelcome pop-ups have topped the list as the most stressful and annoying website faults, according to a new study.

As part of the study, UK website design company Cyber Duck UX Agency launched three websites – a clothing and accessories e-commerce site, a general news site, and a tech and gadget review site – with numerous user experience faults, and then measured the blood pressure of the 1,100 participants when using the sites.

The study measured which of the website design flaws were most stressful for the participants, leading to the largest increase in blood pressure.

“Many of us have become accustomed to using various websites every day for a multitude of reasons,” the report said.

“Whether it be online banking or shopping, most of us want our user experience with a website to be as flawless and enjoyable as possible.

“Unfortunately, this is not always the case.”

It found that slow loading pages caused the most stress among the participants, with blood pressure levels rising on average by more than 20 per cent, from 111 mm Hg to 134 mm Hg. The average load times for pages on the websites were between 8.8 to 10.5 seconds, which was labelled “frustrating” and “excruciating” by some participants.

Those involved with the study said that a load time of more than five seconds is “inconvenient” and “unacceptable”.

The next most annoying website issue was a high number of pop-ups, including for newsletter subscriptions, discount codes, sale awareness and trial offers.

These pop-ups caused the blood pressure of participants to rise by 20 per cent, from 108 mm Hg to 130 mm Hg.

Other issues that were stressful for the participants included auto-play music (20 per cent), broken pages (17 per cent) and auto-play videos (16 per cent).

Auto-play music was listed higher than auto-play videos by the participants as they said it was easier to find the source of the video and turn it off.

Difficult-to-read fonts were labelled “unwelcome” and “inconsiderate” by the participants, leading to a 13 per cent increase in blood pressure.

At the other end of the scale, participants were largely unbothered by disorientating animations on the websites, with this issue only leading to an increase in blood pressure by 5 per cent.

Having multiple image sliders, or carousels, was only just in front of the disorientating animations, creating an increase in blood pressure of the participants from 99 mm Hg to 109 mm Hg.

The users said that a website that had more than three image sliders on a single page was “excessive” and “oversaturated”.

According to Cyber Duck UX Agency, the age range of the participants was 20 to 58 years old, and none had any significant health conditions, or had a working or educational background in information systems, web development or design.

All participants said that they were either “very confident” or “confident” using the internet.

Each participant spent an hour dealing with a certain issue on the three different websites, with 20 minutes for each site. Their blood pressure was measured five minutes prior to and five minutes after the one-hour browsing session.