I used to play on a PC that didn't even meet the minimum specs. When I played on large maps I would go into the world editor and delete parts of them, mostly trees and other scenery. Just remember to not save the level
You can save it without a problem. If you want the default map back, just go to the levels folder in your user folder and delete the changed map there. Then your changes are reverted.
There is an Italy lite map on the repo but if you just installed it then it does take a while to load
https://beamng.com/resources/italy-lite.7074/ https://beamng.com/resources/utah-classic.11431/ https://beamng.com/resources/0-4-0-6-east-coast-usa.22197/ https://beamng.com/resources/0-3-industrial.22186/ https://beamng.com/resources/0-4-0-6-hirochi-raceway.22198/ https://beamng.com/resources/techdemo-gridmap.21989/