Gameconfig repacks like the 103501 are often created by enthusiasts or developers who want to:
While you can manually edit the XML file, a "repack" is generally preferred because it has been tested by the community for stability. It balances the "Pool Sizes" (memory allocations) so that you don't accidentally set a limit too high, which can cause lag or stuttering even on high-end hardware. 103501 gta v gameconfig repack