More than one in six web users claim a slow loading website puts them off online shopping, says OpTier.

Research by the company, which develops business transaction management software, revealed that 75 percent of Brits said they use a combination of the high-street and online stores to complete their Christmas shopping, with 70 percent planning to spend around £220 online.

Furthermore just 16 percent said they would steer clear of internet shopping completely.

"If one retailer fails to deliver, shoppers will simply move on until they find one that can. It's the nature of supply and demand," said Colin Rowland from OpTier.

OpTier said 41 percent of Brits said 'simple and reliable processes' was the most important factor when shopping online, while 20 percent looked for quick delivery times and 19 percent wanted a site that was easy to use.

"In the last 18 months, customer expectations of their online experience have evolved significantly. It's no longer enough to have a great front end - increasingly consumers care about what goes on under the hood because that's what impacts their experience the most," added Rowland.

Neil Barton, director of internet hosting company Hostway agreed with Rowland's comments.

"Last December, shoppers spent £4.6 billion online, but there is a real danger etailers could miss out on revenue if shoppers leave sites due to their being slow or poorly performing," said Barton, citing research from Forrester that revealed consumers get restless e-commerce sites take longer than two seconds to load.

Furthermore the survey said that 40 percent of web users would abandon a web page if it took more than three seconds to load.

Barton said if e-commerce sites are unprepared for the heavy levels of traffic that might slow them down then they risk losing money and potential customers.

"Just as stores on the high street hire extra workers at Christmas, so online stores should invest in extra infrastructure to cope with increased demand," added Barton.

According to Dan Sutherland, CEO of hosting company Carrenza, retailers don't need to invest heavily in IT hardware to ensure their websites continue to load quickly.

"Opting for a hosted provider to look after their website, businesses can cost-effectively prioritise their 'virtual shop floor'," said Sutherland.

"This will ensure their online systems remain running despite the seasonal peaks in demand, but without them having to pay for that level of capacity all year round."

"Given the number of businesses that rely on their Christmas revenue, it is essential that investment in their 'virtual shop floor' is as much a priority as their physical one," he added.

New: Try out PC Advisor's virtual BlackBerry

Broadband speed test

See also: Two thirds of Brits to shop online for Christmas