How a Hacker Cut GTA Online’s Loading Time by 70% Using Code Hooks

Players have complained for years that GTA Online takes excessively long to load, often exceeding five minutes even on high‑end hardware. A hacker used a decompiler and the Luke Stackwalker tool to sample the game’s CPU stack during startup, revealing that most of the delay was caused by a single inefficient code path.

Identifying the bottleneck

Two functions were found to monopolize the CPU. One of them called sscanf on a roughly 10 MB JSON file containing about 63,000 entries, likely related to the in‑game store. The function read each character of every entry sequentially, resulting in an if statement that executed (63,000² + 63,000)/2 ≈ 1.98 billion times.

Meanwhile, memory, GPU, and disk usage remained largely unchanged, confirming that the problem was purely CPU‑bound.

Fixing the issue

The hacker applied two main patches:

Hooked strlen to cache string lengths, avoiding repeated scans of the same data.

Replaced the massive if loop with a hash‑map lookup, eliminating the need for quadratic comparisons.

After recompiling and injecting the modified DLL, the loading sequence dropped from about six minutes to roughly one minute and fifty seconds on the same hardware (AMD FX‑8350 and GTX 1070).

How to apply the patch

The patched DLL and a small script are hosted on GitHub. Users can clone the repository and copy the DLL into the game’s root folder:

git clone --recurse-submodules https://github.com/tostercx/GTAO_Booster_PoC

Then replace the original DLL with the provided one.

Original blog post: https://nee.lv/2021/02/28/How-I-cut-GTA-Online-loading-times-by-70/

GitHub repository: https://github.com/tostercx/GTAO_Booster_PoC