I do not agree with the sibling comment saying that this problem only looks simple and that we are missing context.
This online gamemode alone made $1 billion in 2017 alone.
Tweaking two functions to go from a load time of 6 minutes to less than two minutes is something any developer worth their salt should be able to do in a codebase like this equipped with a good profiler.
Instead, someone with no source code managed to do this to an obfuscated executable loaded with anti-cheat measures.
The fact that this problem is caused by Rockstar's excessive microtransaction policy (the 10MB of JSON causing this bottleneck are all available microtransaction items) is the cherry on top.
(And yes, I might also still be salty because their parent company unjustly DMCA'd re3 (https://github.com/GTAmodding/re3), the reverse engineered version of GTA III and Vice City. A twenty-year-old game. Which wasn't even playable without purchasing the original game.)