Cent, like Chrome, stops showing icons on tabs if there are many tabs open, even if there's more than enough space to do so (I use square tabs). There's no reason to do so. On FireFox with a custom style I made icons always visible, even if tabs are 5px wide. This makes tabs bar usable with 100+ tabs.
Another thing I did: I made loaded tabs a bit wider, so I have a swarm of tiny unloaded tabs and a number of loaded ones (that is, ones I visited since starting the browser) which are 5px wider.
Another thing I did: I made loaded tabs a bit wider, so I have a swarm of tiny unloaded tabs and a number of loaded ones (that is, ones I visited since starting the browser) which are 5px wider.