Your issues may be video card related. Yours seems to have the old DDR3 type memory which is very slow compared to the GDDR5 used in gaming level cards.
Also, as you may have heard/read, speaking of the Nvidia cards, the tens indicate the relative power within the video card series, the hundreds telling the generation. #45 is at the lower end, the serious gaming level starting from #60. Most likely you should tame your settings quite a lot for a decent gameplay.