UK consumers spent £38bn online last year, yet retailers are missing out on up to £5.7 billion worth of those sales, as a result of problems with their websites including slow loading pages, according to a new analysis.

A survey of two thousand consumers found that on average, buyers abandoned 5.5 online transactions per person over the last 12 months, with the average spend pegged at £30. Forty six percent blamed slow loading pages.

Over eight in 10 consumers said they would be dissuaded from buying goods on a website that performed badly, and would even consider not going to the company's stores. A quarter were frustrated with advertising on retailers' sites, and 16 percent said they did not like the navigation on many sites.

Seven in 10 consumers said that if they regularly purchase goods from a particular website they should be rewarded with a better web experience than those who are just browsing.

The decision by many retailers to use images and video heavily to make their websites more attractive was having a negative impact on performance. Some 70 percent of consumers said they were frustrated by how long it takes many websites to load images, and by the stop/start nature of video.

Neil Barton, director at hosting and virtualisation firm Hostway, which commissioned the survey with application delivery provider Zeus Technology, said that "over two thirds of the respondents were wasting up to two and a half days a year reloading or waiting for web pages to load properly."