Investing.com - Investors are already looking forward to another muscular earnings season, but don't expect the second-quarter performance to rival that of the first, which was the best in more than a decade.FactSet is forecasting a double-digit increase. The 2017 corporate tax cut will once again help earnings, but not as much as in the previous quarter.A record number of companies posted better-than-expected earnings in the first quarter.In the second quarter, all 11 sectors of the S&P 500 should post gains.Energy is expected to lead all sectors with a triple-digit increase, thanks to the powerful recovery in oil prices, according to the Wells Fargo (NYSE:WFC) Investment Institute. Earnings for the materials, financial and information technology sectors are all forecast to rise 20% or more, according to Wells Fargo.PepsiCo (NASDAQ:PEP), Delta Air Lines (NYSE:DAL), Citigroup (NYSE:C), Wells Fargo and JPMorgan Chase (NYSE:JPM) kick off earnings season the week of July 13th.