Devon Energy Corp said on Tuesday it would lay off 300 workers, roughly 9 percent of staff, part of a plan to streamline operations and boost the shale oil producer’s sagging returns and stock price.  The cuts will affect all areas of the company’s operations, not just its Oklahoma City headquarters. Staff will be let go “in the weeks ahead,” Devon said in a statement.  Shares of Devon jumped nearly 7 percent on Tuesday to close at $33.60 on the New York Stock Exchange. The stock had been up about 5 percent earlier in the day, in line with broader markets and oil prices [O/R], but kept rising after the layoffs were announced.  Devon, like many of its shale peers, has come under pressure from Wall Street in recent months to focus less on production and more on ways to boost shareholder returns. The company’s stock had, as of Tuesday’s close, lost more than 20 percent of its value in the past year despite a jump in oil prices.  Devon said it expects the cuts to help save $150 million to $200 million by 2020.