First, understand this is not personal. I liked this extension so much, I tried it 3 times over a period of 2-3 months. But each time - the last being an hour ago, it broke my browser, then my entire computer - so much so, that I had to do a dirty shutdown to get it back - all 3 times. A yellow script error bar flashed, informing me that this extension was slowing down Firefox. Then my entire computer froze - and black-screened this time. No other extension or program, on or offline, has ever caused or provoked such a situation with this computer. I wish there was a simple highlighter extension that was usable; I need one desperately. It's unfortunate that this one is so destructive in my case, because it is exactly what I need. I truly loved this extension. It is obvious that a lot of work has gone into it.