Larian Studios Forums Divinity: Original Sin 2 - The Modding Dungeon Divinity - Original Sin 2 - Modding General Error messages?

So I gave up on trying to load someone else's mod , and tried to just create an addon project from scratch, but I still get a load of about 20 error messages, like
File version of texture atlas 'E:/Games/Divinity - Original Sin 2/DefEd/Data/Public/Shared/GUI/Icons_DOS2_Skills.lsx' is deprecated, and should be re-saved to optimize load time!

How do I go about resaving all these files to optimize loading times?
Because I Really need to optimise load times.
After half an hour, my quite high end PC is still stuck on loading 7% of 1298MB.