Updating your version of flash
At one point, I was viewing a single web page and the Chromebook was sluggish.I used Shift-Escape to bring up the Google Chrome Task Manager and saw that the Flash plugin was using a lot of ram and CPU cycles.When the installed version is old, it tells you what the latest version is for your browser/OS. The bad news is that it punts on the Chrome browser and IE on Windows 8.In both cases it says that Flash should be updated automatically, so fuggedaboutit, you're fine.
What's new here is the recommendation to use click-to-play as a defensive tactic in Chrome.
I killed the Flash process, but it soon came back even though I was still on the same web page.
Annoyingly, if you want to block Flash content by default, Guest users on Chrome OS need to change the plugin action to "Let me choose when to run plugin content" every time they logon. FLASH PLAYER on WINDOWS (needs to be revised for Windows 10) My Recommendation: (last updated Feb 15, 2015) Windows users should only use Flash in the Chrome browser.
In early Feb 2014 it was only displaying the first 3 sections of the Flash version number, which has 4 sections. As of May 2015, the bug was back, it reported only that v17.0.0 was installed.
The bug still existed July 15, 2015 (Chrome on Windows 7 reported that version 18.0.0 was installed).