Google is cramming more and more functionality into Chrome. That's a good thing, but the added weight is beginning to be felt by users. Add to this instability issues and Chrome doesn't look like the nimble, rock stable browser it was when it launched in 2008.
Google engineers have known about this for a while, there is an effort to rewrite some of the underpinnings, for better cross-platform support and more extendability.
Several technologies and features, including hardware acceleration for the UI, can't be introduced until Google is done with the rewrite.
One problem that has been plaguing many Chrome users lately underlines just how bad it's gotten. Many, many people are reporting Chrome crashes, the entire browser freezes and has to be forcefully shut down, when using YouTube.
The bug is highly reproductible, for those affected by it, every time they would close a YouTube tab the browser would freeze and not come back.
The issue is linked somewhat to Adobe Flash, since it's the video player in YouTube that is causing the freeze. Disabling Flash gets rid of the bug, but also of YouTube. Some users report that switching to HTML5 mode doesn't necessarily fix the issue.
One workaround for the issue is to stop the video download, right click on the video player and select "Stop Download" and then close the tab.
Chrome's multi-process architecture should prevent these kinds of issues. Users should be able to kill the plugin process, running Flash, or even the YouTube tab process, crashing the plugin or the entire tab and the ones linked to it, but without having to close Chrome. That doesn't happen unfortunately.
However, Google has said that the issue has been fixed. It appears that the issue was related strictly to YouTube, so no Chrome update has been issued, rather YouTube has repaired the bug.