Food and gift basket sales increased 4.7%, but total e-commerce, which includes online and telephone orders, increased less than 1%.
The retailers topped Internet Explorer and Firefox consistency tests, respectively.
Overstock.com had the best consistency score for Internet Explorer testing among large retailers tested in April, Compuware Gomez says. Last month, the retailer had the most consistent Internet Explorer site loading time with a variation of 0.70 seconds. OfficeMax.com had the best Firefox consistency score at 0.68 seconds.
OfficeMax.com (0.72 seconds) placed second in Internet Explorer tests. Dell.com (0.85) placed third, followed by OfficeDepot.com and QVC.com tied at 1.08 seconds.
In Firefox testing, Apple.com had the second-best time with a variation of 0.85 seconds. QVC.com was next (1.23 seconds), followed by OfficeDepot.com (1.24) and Overstock.com (1.32).
The average Internet Explorer consistency score among the 21 retailers measured in April was 1.42 seconds. The same group of retailers produced an average Firefox score of 1.81 seconds.
The consistency ratings take into account differences in the speed of web page delivery across multiple visits.
Click here for the full test results.