Silverlight = null

The culprit...

    Silverlight.WaitForInstallCompletion = function() {
    if (!Silverlight.isBrowserRestartRequired && Silverlight.onSilverlightInstalled) {
        try {
            navigator.plugins.refresh()
        } catch (a) {
        }

        if (Silverlight.isInstalled(null) && !Silverlight.__onSilverlightInstalledCalled) {
            Silverlight.onSilverlightInstalled();
            Silverlight.__onSilverlightInstalledCalled = true
        } else {
            setTimeout(Silverlight.WaitForInstallCompletion, 3000)
        }
    }
    };

I've seen this popping up on more and more sites... if you're getting janky performance suddenly on sites that are normally fine this might be the culprit.

I'm on Linux and have never even tried to install Silverlight... looks like they're pretty optimistic about changing that.

Silverlight = null

In JS console == fixed.

That is all, g'day.