Costco (COST 0.36%) is one of the best-performing large-cap retail stocks over the past five years. It continued to show why it's one of the top retailers when it once again reported strong results for its fiscal first quarter. The stock is now up more than 50% on the year and about 235% over the past five years, as of this writing.Let's take a closer look at the retailer's most recent results to see whether the momentum in the stock can continue.Another stellar quarterThis was the first quarterly report si ...