Why does chrome use excessive amounts of CPU?

Use Chrome's built-in task manager to see what part of Chrome (page, plugin, etc) is using CPU.

To access it, just press Shift+Escape (or right click the window decoration and select Task Manager)

Switching to integrated GPU solves the high CPU issue for me.

I have the following system:

Graphics:  Card-1: Advanced Micro Devices [AMD/ATI] Trinity [Radeon HD 7600G]
           Card-2: Advanced Micro Devices [AMD/ATI] Mars [Radeon HD 8730M]
           Display Server: X.Org 1.17.1 driver: fglrx
           Resolution: [email protected], [email protected]
           GLX Renderer: AMD Radeon HD 7600G
           GLX Version: 4.4.13374 - CPC 15.20.1013

I've switched to the Integrated GPU (instead of High Performance discrete) in Catalyst Control Center (Administrative). After reboot the high CPU in Chrome is completely gone.