It is hard to say what exactly that triggers this. It could be some extension or one of the open pages etc. Especially after hibernation when Chromium is swapped to the memory; my system can become slow and useless.
So how do we drill down to the exact problem in Chrome/Chromium?
Simple!
Just hit <SHIFT> + <ESC>
This will pop up a process monitor:
It will show what process that takes the most juice (I did not know that adblock took that much) and let you cancel them.
Try removing extensions you do not need and tune it to your liking - it might help.