Rated 4 out of 5 stars
Good addon but the "thumbnail updating" is causing massive CPU usage (100%) when scrolling on some sites like TabMix Plus forums.
It took me quite a bit of effort to find out from all the extensions that i have that this was causing the slow downs/freezing. This was quite a surprise that it keeps updating thumbnails even when not using Showcase, this option should be turned off by default.
Are you sure that this problem is caused by Showcase? The only scenario in which Showcase will use CPU while not active is if the cache is active, which is not by default. I tried to reproduce your issue, so I would really appreciate if you could send me more information about it by email.