I was using "Advanced Font Viewer" démo version, as it is fast and packed with functions.
I'm now looking for a free alternative like 'Advanced Font Viewer' (it is not on alternativeto, for the moment;P).
"NexusFont" interface is really attractive, and I have 784 installed fonts, even I did not wait 5 seconds for loading all!
It is possible to create groups, these are folders, we can then place the font according to our choice (personally I have created 4 groups: classical, Graffiti, Calligraphy, Special).
I'm still testing but its seems promising!
A good small tool which will serve me long.
Too bad the last update date since 2012 :(
But the functionality is there, it's perfect.