Twitter Inc beat Wall Street’s revenue target in the fourth quarter but the pace of its user growth weakened, adding pressure on embattled Chief Executive Dick Costolo. Shares of Twitter, which initially slipped after the release of the financial results on Thursday, recovered and were roughly flat from their closing price of $41.26 in after hours trading. Twitter said it ended 2014 with 288 million monthly users, up 1.4 percent from Sept. 30. The pace of user growth was Twitter’s slowest in several quarters.