A player who claimed to reduce the load times of Grand Theft Auto: Online by up to 70 percent has been rewarded by Rockstar for his work.
Edit: The update has gone live and loading times are significantly reduced.

Rockstar recently confirmed that the player had indeed found a bug causing the awful loading times and that a fix will be officially coming in a future update.
It was only at the beginning of this month that a Github user claimed they had discovered a way to reduce the loading times of Grand Theft Auto: Online by up to 70 percent. They also release the fix to the public with the understanding that this is just a “proof of concept, not for casual use.”
There was also a detailed analysis posted the Github user which breaks down exactly what went wrong with the loading times, and how it was fixed. Although the breakdown is rather technical, but the simple version is that the slow loading times were being caused by “a single thread CPU bottleneck while starting up GTA: Online” and estimated that it “shouldn’t take more than a day for a single developer to solve.”
Rockstar say it actually took a little bit longer than that, but they confirmed that the findings were correct and that a fix is on it’s way.
“After a thorough investigation, we can confirm that player t0st did, in fact, reveal an aspect of the game code related to load times for the PC version of GTA Online that could be improved,” Rockstar said in a statement. “As a result of these investigations, we have made some changes that will be implemented in a forthcoming title update.”
Rockstar then went on to confirm that they have been in touch with the Github user, and that they would like to thank him for his efforts. They later confirmed they had awarded him $10,000 through the Rockstar Bug Bounty Program. The program is usually reserved for finding security or privacy issues with Rockstar services but they awarded him the bounty anyway “as an exception”.
Rockstar didn’t confirm when the update would go live with the bug fixes, but they did say the work had already been done on the development side so hopefully we wont have to wait long.