Memory Efficiency Composite Score
Our memory efficiency composite score is achieved through a series of four tests. First, we get a baseline memory usage reading for each browser with just one page open (Google.com). Next, we open an additional 39 tabs (the remaining Top 40 websites), and record the new 40-tab memory usage total. The extra 39 tabs are then closed, and the memory usage is recorded once again. Finally, we wait an extra two minutes and record the usage once more. The memory efficiency score is determined by the difference between a browser's single-tab memory usage total and the final recorded total after closing 39 tabs and waiting two minutes. A perfect score here would be zero, meaning a browser uses no more resources after a heavy workload than when it's first opened.
We run this sequence for three iterations, and unlike our start and page load time tests, the memory efficiency tests utilize live Web sites.
As usual, Chrome takes the lead in memory efficiency, followed closely by Internet Explorer in second place and Firefox in third. Opera once again lags behind the others, placing last. Interestingly, all four Web browsers return more RAM to Windows 8 than Windows 7.
The charts below contain the measurements of all four memory efficiency tests.
Chrome and Opera release memory back the OS immediately upon closing tabs, while the Internet Explorer and Firefox memory totals decline more gradually.