Lastpass addon slows down firefox so that it becomes unresponsive at all

I Use FF 67.0.4 on Ubuntu 18.04. Out of the sudden after opening my FF it stopped loading pages. After a series of blind tests I figured it was because of the lastpass addon: when I disabled it, FF started working again. Before it was not loading any content.
Surprisingly, I didn’t change any settings before the bug started to appear.