AMP Font Viewer 
I've used it for years on my windows work boxes!
I keep a minimal number of fonts installed into Windows ... when windows needs to reload more than a hundred or so fonts each time it redraws the page, it really does hamper the performance of your system ...
Benchmark your system with only 40 fonts installed ... and then run the exact same benchmark with 300 fonts installed, and once more with 1000 fonts installed ... and you will see the performance degradation before your eyes!!