Tesco has enjoyed its strongest performance in 18 months with sales up 1.1% in the past 12 weeks, as the industry price war created record levels of deflation, according to fresh data from Kantar Worldpanel.Increasing sales have helped Tesco put the brakes on its skidding market share, which is down just 0.1 percentage point compared with last year to 28.7% and down from 29.% a month ago.The rival worst hit by Tesco's resurgence was Asda, where sales were down by 2.1% following indications of trouble in a recent trading statement.Morrisons and Sainsbury both grew slower than the market, suffering a 0.4% and 0.5% sales decline respectively.Fraser McKevitt, head of retail and consumer insight at Kantar Worldpanel, said the price war has seen deflation driven to a record low of -1.6%."A combination of lower general inflation and the grocery price war has saved shoppers £400m in the past 12 weeks, with deflation driven to a record low of -1.6%."All of the major supermarkets are cutting prices to win shoppers, especially within everyday staples such as eggs, vegetables and milk. Retailers are focusing their efforts on simple price cuts rather than complicated 'multibuy' deals."