Testing memory efficiency is a multi-step process. First, we open each Web browser with one tab and record its memory usage. We then open 39 additional tabs and re-record the memory usage total. Next, we close those 39 tabs and record the memory total once more. We've removed the second reading after closing 39 tabs, and instead just wait for the big usage drop to occur for each browser, and record once.
All pages are opened in each browser before testing, so the memory tests are loading cached pages; the browsers are started hot. Memory usage totals are now taken using Chrome's built-in about:memory page instead of Windows Task Manager because it is far more accurate dealing with multi-process browsers such as Chrome, IE10, and Opera Next. We also combined our remaining three memory usage readings into a single chart.
IE10 takes the lead in single-tab usage at just 40 MB, followed by Opera Next at 75 MB. Opera 12 takes third place, with Firefox and Chrome placing fourth and fifth (respectively) at around 120 MB with a single tab open.
With a heavy-duty workload of 40 tabs, it's Firefox that uses the least amount of memory. Opera Next places a distant second with a tally of almost 1.2 GB. Close behind in third place is IE10. Chrome and Opera 12 practically tie for last place, with both browsers just over the 1.5 GB mark.
After decreasing the workload back down to a single tab, Opera Next takes the lead. Chrome is in second place at just under 200 MB, followed by IE10 and Firefox 22 in third and fourth place (respectively) at around 270 MB each. As usual, the current version of Opera ends up in last place, holding onto a whopping gigabyte of RAM.
It looks like Opera Next is a move in the right direction for all three memory usage scenarios.
Next, the Single Tab figure is subtracted from the 39 Tabs Closed number to see how much "bloat" remains after decreasing the workload (closing tabs).
The championship-ineligible Opera Next gets closer to its original single-tab total than any other browser at a difference of just 65 MB. As you might expect, Chrome is close behind with a difference of 76 MB. Firefox 22, though it uses the least amount of memory under load, retains 165 MB more than before the 39 additional tabs were opened, placing third. Surprisingly, IE10 places fourth. Chrome's about:memory page is clearly much better at tallying Internet Explorer's multiple processes than Windows Task Manager. Opera 12 again winds up in last place, retaining nearly an entire gigabyte.