Efficiencies drove a quarterly earnings beat.Swimming pool manufacturer Latham Group (SWIM 45.18%) rode a wave of cost cuts to better-than-expected earnings. Investors are diving in, sending Latham shares up 42% as of 2:30 p.m. ET.A more efficient pool makerLatham designs and manufactures in-ground swimming pools in North America, Australia, and New Zealand. In the quarter, the company earned $0.11 per share, up 55$0.01 per share consensus estimate.Revenue fell by about 1 ...