The same here. It isn't constant, though. CPU usage is considerably higher using Chrome compared to Safari. All tabs have their own process, that takes from 0.1% to 1.75% of the processor usage. Flash player takes about 1% idle, with some embedder Youtube videos loaded. Chrome itself takes anything from 1% to 30%. Sometimes the tab's process may take more CPU usage. All that is while idling. When loading pages, Chrome takes all the CPU for itself, so lag is the most apparent manifestation of this problem.
I have attached a screenshot of the CPU usage when loading a page on this forum.