Nvidia Dynamic Super Resolution (DSR) not working properly

Since Nvidia released patch 344.48 Kepler and Fermi GPUs have support for the new DSR technology which was originally developed for Maxwell based GPUs (for those that don't know DSR is basically rendering a 4k resolution in a 1080p monitor).

I was trying LoL in DSR 3640x2160 and it works nice but every time I hover my mouse over any selectable unit OR target any unit present in my screen dramaticaly reduces FPS from 60 to 1-3 (targeting a unit that is not present on my screen doesn't trigger this issue)

My build: Core i5 3570k @ 3.4 Ghz 8 GB RAM Corsair 1333 Mhz EVGA GTX 780 Ti Classified GIGABYTE Z77X-UP4 TH ASUS VG248QE 144Hz 1080p Monitor