I get low FPS with a PC high tech

[InVizO]

Hi there. I dont know why but I have a fall of FPS when I play and I have a PC with Raccomanded Setup exceeded.
I have 60 FPS on dungeon-trial but if I am on Mor'Dhona I fall to 25-30 FPS (it can depend from many people are there ok but this much fall?) and if I'm going (for example) to Aleport I stay on 50-55 FPS and if I roteate the camera sometimes I fall to 25 FPS and then go back to 50-55 . What can it be?
This is my PC:
Windows 8.1 Pro 64 bit
nVidia GeForce GTX 750ti 2 GB
AMD Phenom 965 X4 BE 3.6 Ghz
8 GB Ram 1600mhz
Drivers are last and I play with Maximum graphics with 1440*900 resolution (so not HD)
Thanks

A GTX 750 is not a gaming video card, Nvidia has always began their gaming lines with a 6 for entry level and 8 for serious. Hence the 760 and 780. I already replaced my 760GTX because of low FPS in this game, be happy with mostly low to medium settings or upgrade.

edit: Poor DX9 optimization caused by the game developers does not help either.

[Spot]

A GTX 750 is not a gaming video card, Nvidia has always began their gaming lines with a 6 for entry level and 8 for serious. Hence the 760 and 780. I already replaced my 760GTX because of low FPS in this game, be happy with mostly low to medium settings or upgrade.

edit: Poor DX9 optimization caused by the game developers does not help either.

Agree completely.