NVIDIA GeForce GTX 750Ti
Intel Core i3 4160
4 GB of Ram
1 Terabyte capacity
etc.. even it's a new computer
I dont think it's the pc specs to be honest, but i wonder what the problem could be
Some Times its better than a Game use the Nvidia Graphik cart,but some times it used the Intigrated
To Check these go to your Taskbar and rightclick on Nvidia Geforce Expierience
Then Click on Nvidia System(Here anything,its in german by me C

then Start TErraria Once and close it
Go in the Nvidia System.... and click on 3D Setting
Click on Add and Chose Terraria
Then Click on "Add Chosen Programm" or so,you know its german for me C:
Here a Screen how it sould look
Then go to 2.and Chose there your Nvidia Graphik Card
I think you have an other Problem with your Frame Drops,but if Terraria dont used the Better Graphik Card it should Help C:
If its already use the Nvidia Graphic Card,all what i sayed is Useless C: