Will up dating a video card work or do you need to up date other things. My frame rate jumps from 45 to 60. In GV's it drops from 16 to 25. {AHIII)
Shilo, such a large drop in fps makes me wonder about a couple of things. First, there is an option in graphics detail that disables clutter (in fact there are two, I suggest to make sure both are disabled: clutter in flight is the other), next HTC has given you a lot of sliders that you can move to the left for more performance.
While on the ground there are more detailed textures that are rendering (for example: look at the sky and see fps soar) Unless you are setting on top of a hill, increasing detail range to an extent would be wasteful, for moderate play. Of course, these are only my opinions, that unless I am sitting in your seat I could not confirm.
DxDiag can also point to other areas on your computer not directly related to gpu hardware that could be causing loss in performance. The best understanding that I have gained from GPU performance has been from comparisons.
Try this
http://www.gpureview.com/show_cards.php or other sites that give you comprehensive data on GPUs that are known to perform well with HTC and then look at things like dedicated video memory, bandwidth, memory type, etc. you may have a better idea of what to ask for .... keeping in mind the power supply requirements which are less of a restriction for some cards and more for others.
Lastly, if you wish to upgrade, then YES do it, but realise ONE THING, ratio of money spent does not necessarily directly relate to 100% bells and whistles..... in other words, no matter what rig you buy or upgrade to, there will be a need for sacrifices and / or tweaked settings.