Greg Leffel, an investor in Columbus, Ohio, said he relishes cash deals as much as he dislikes home loans. Investors like Leffel helped spur all-cash home purchases to a record 43 percent of U.S. deals in the first quarter, more than double the share a year ago, according to data firm RealtyTrac Inc. Cash is keeping residential sales trudging along while mortgage lending plummets, hurt by rising interest rates and stiff credit requirements.