Performance JSON x Properties in Java

Question

Good night.
I used to use several files .properties to save the data from the desktop application I develop. I studied the possibility to exchange these files for files .json, because I see that many software in the market use this format.
While performing the exchange, I noticed a loss of performance when loading the data. So I’d like to ask you a few questions:
1) Is there any good practice that can improve the performance of the application?
2) To save several files, each containing a java object inserted by the user through the application, .json is the best option or there is another better?
The idea of these files is to facilitate portability from one computer to another and the exchange of information between different users.
Follow the commit link I made with the switch:
https://github.com/coppolaop/DungeonManager/commit/0ac90b905f02156eef43838b5f2960bf776cba15
Feel free to stimulate the debate, I think it can add a lot.
Thanks in advance for the help.

Answer 1

I found an article talking about the performance of conversion libraries. The research cited in it compares the most used libraries, I’m taking it as my answer first question, to good practice depends on the project and its frameworks. About the second question, I keep believing that it’s a convention issue, as the community adopts JSON a lot nowadays due to REST, I believe it’s a good option.