I don't know anything about the creative mode, but as for the main battle royale itself...
EVERYTHING.
Massive online multiplayer games are hard on cpus. A dual core such as the I3 2120 is not sufficient.
4GBs of ram is too little as well. With such a low amount, you can't afford to have anything else running in the background, as it will take from the very few resources your cpu already has. [Exclude windows, you have to have an OS.]
While GT 1030 can be run at 1080p resolution, it runs best at 720p.
It's a combination of those 3, and maybe more depending on the rest of your setup.