The team has been working on addressing this; here are some cases that have recently been improved on trunk:
Before: Renderers for background tabs had the same priority as for foreground tabs.
Now: Renderers for background tabs get a lower priority, reducing idle wakeups on various perf test, in some cases by significant amounts (e.g. 50% on one test).
Before: On a Google search results page, using Safari's user agent to get the same content that Safari would, Chrome incurs ~390 wakes over 30s and 0.3% CPU usage vs. Safari’s 120 wakes over 30s and 0.1% CPU usage.
Now: 66% reduction in both timer firings and CPU use. Chrome is now incurring ~120 wakes over 30s and 0.1% CPU use, on par with Safari.
Before: On capitalone.com, Chromium incurs ~1010 wakeups over 30s vs. Safari's ~490 wakes.
Now: ~30% reduction in timer firings. Chrome is now incurring ~721 wakeups over 30s.
Before: On amazon.com, Chromium incurs 768 wakups over 30s and consumes ~0.7% CPU vs. Safari's 312 wakes over 30s and ~0.1% CPU.
Now: ~59% reduction in timer firings and ~70% reduction in CPU use. Chrome is now incurring ~316 wakeups over 30s, and 0.2% CPU use, on par with Safari at 312 wakes, and 0.1% CPU use.
The Chrome team has no intention of sitting idly by (pun intended) when our users are suffering. You should expect us to continually improve in this area.