The 1030 will be almost three times as fast. But there is the VRAM delima as well. More and more games are coming out that require 3 or 4GB VRAM so the options will be limited.
You would be MUCH better off saving a few extra dollars and getting a GTX 1050 or an RX 460. Both will significantly outperform a GT 1030 (which is already way faster than the GT 730) You'd still be limited by the VRAM but you will get MUCH greater performance out of either of those on games that it will run. If you have a solid CPU I've seen benchmarks of people running Skyrim:SE on Ultra 1080p with a 1050 Ti at 50fps. Meaning you will get at least 30fps on Ultra 1080p Skyrim:SE with a 1050 or an RX 460, 1030 you'd probably be lucky to get 30fps on medium.
The...