UK smartphone users are being deterred by retailers' poor mobile websites, costing the firms as much as £4 billion in lost revenues, according to a study conducted by web site optimisation company QuBit. Part of the problem, according to the study, conducted by web , is a lack of "thumb friendliness," redirection from desktop to mobile versions and website load speeds. The problems, which QuBit says are costing individual retailers as much as 12 per cent in annual revenues, can be remedied with minimum investment by the retail firms. According to QuBit, less than 5 per cent of UK retailers have optimised their websites for mobile users, despite the growth in the percentage of retail web site traffic being generated by mobile devices--tripling year-on-year to 15 per cent in 2011. Article