One of the most important parts was the Omnibox which allowed you to search Google (or indeed any other search engine) from the address bar just by typing your query in there. It has probably over the years saved me quite a significant amount of time.
However, recently it has been running very slowly indeed. Chrome in general was still running very smoothly and quickly. However, the Omnibox was sluggish often taking several seconds to registers my key presses. It never crashed; it was just slow.