Assegnate 2 su 5 stelle

This functionality should be built-in in Thunderbird, but unfortunately it isn't. And unfortunately again, this seems to be the only extension that tried to tackle this, and as others have noted, it leaves a lot to be desired in terms of performance. In fact, the flickering and the general slow-down got so bad that I had to disable it. I hope the developer will fix those obvious issues.

Questa recensione riguarda una versione precedente (1.2.2) del componente aggiuntivo. 

Thanks for your feedback. The flickering is due to Thunderbird high refresh rate and I can't do much about it (or just slow down even more Thunderbird...).
However you can still use the add-on in the message panel by disabling in the settings the display in the inbox list.