Updated from May 25 with comments form Jim Cramer and Jack Mohr

Costco (COST) - Get Report may be feeling the heat from online juggernaut Amazon (AMZN) - Get Report , but at least it continues to dominate its closest bricks-and-mortar competitor, Walmart's (WMT) - Get Report Sam's Club. 

The warehouse giant reported Wednesday evening that earnings rose 6% from the prior year to $1.24 a share for the third fiscal quarter ended May 8. Wall Street had anticipated earnings of $1.22 a share.

Total revenue rose 2.7% year over year to $26.8 billion, narrowly missing forecasts for $27.1 billion. Excluding the impact of gas price deflation and the strong U.S. dollar, Costco's third-quarter same-store sales rose 3%. 

While Costco didn't exactly set the world ablaze with its sales and profit growth in the quarter as it has done historically, it did continue to outperform Sam's Club in several key areas, likely due to its relentless focus on keeping prices low and the resilience of its higher-income members.

Costco's U.S. same-store sales, excluding gas deflation and the dollar's strength, increased 3% in the quarter compared to a paltry 0.1% improvement at Sam's Club. Membership fee income for Costco rose by 5.8% to $618 million, compared to a 3.9% gain at Sam's Club. 

Even as Sam's Club is viewed by many retail watchers as being ahead of Costco on the technology front, keeping it simple does seem to continue to be paying off for Costco. 

"If you study Costco, they have won because of the discipline of their model -- and they are unwilling to move away from that discipline," noted Sam's Club President and CEO Rosalind Brewer in a recent interview with Fortune.   

In a new note on Thursday, TheStreet's Jim Cramer and Jack Mohr of the Action Alerts PLUS Charitable Trust Portfolio, said they were "encouraged" by the quarter, adding "we are bullish long term (hence our $175 price target), but expect shares to ramp after the company reports July sales, as we believe customers are awaiting the late-June transition from legacy AmEx to the Citi/Visa co-brand card (the latter of which offers far larger rewards) before spending on big-ticket items."

Costco is a holding in Jim Cramer'sAction Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells COST? Learn more now.