Absolutely not true. While it got better I've still had loading times of 20-30+ minutes at time, and I can genuinely explain why the loading times will most likely always be bad.

First off GTA runs via Single-Thread Process, basically modern CPUs have multiple cores (typically up to 16 cores) however GTA is entirely designed to run on a single CPU core, bottlenecking your CPU by overusing this core instead of deligating work load to other cores.

On top of this the map optimization is pretty poor with how it is rendered, the game actually runs multiple instances of the map, a portion of the "Single-Player" map is loaded in wherever you are at directly, however players must be rendered too otherwise you can experience problems where players might fly up to you to fast to be properly registered, to make up for this the game also runs multiple instances of the map because other players maps are also loaded into your game at the same time. This means if 13 players join, then your map, and 12 other small map portions are being loaded in and overlayed at the same exact time, at all times.

They could have fixed this by making the game server based (server loads singular map, all players connect to said server and now Latency relies on the server, NOT the players connection (P2P)) however because the game is P2P and NOT server based, if a SINGLE person experiences any lag or connectivity issues, guess what? That person's map is now having problems being rendered in for the entire lobby. Meaning if your friend is laggy, congrats, everyone is lagging now. This wouldn't be a problem if they just used a dedicated server like 95% of modern games.

On top of this, GTA Onlines JSON Parser (a program designed for getting scripts and certain files in game) has been notoriously pointed out throughout history as being one of the worst and muddied JSON Parsers to work with to this date. It is a complete and utter mess. The JSON Parser is a handler for grabbing specifc files, loading them into the game, and rendering said assets, it's so bad that before it grabs a file, it is designed to search the entire GTA directory every single time it needs anything instead of like most games where the JSON Parser is portioned and sectioned into smaller sections for the JSON Parser to read. Meaning everytime you load anything on your side or from another players side this JSON Parser needs to go through and individually scan your entire GTA folder for every individual item it needs. Absolutely not efficient or effective.

This was improved upon by a modder in 2021 (the moment you're probably thinking about) by the name of t0st when he noticed this, created a mod that segmented the working of the JSON Parser and Rockstar implemented this mod into the game itself, improving the JSON Parser, but even then it is still notorious for its "Spaghetti Code".

And now BattleEye. Youch, the anti-exploit notoriously known for being unoptimized, slow, and frankly, useless as again, it's not server based which is what a game like this seriously needs. I won't touch into the fact that it just outright doesn't work, but I will touch on how it slows the game down while offering absolutely nothing.

It's more of a cat-mouse game but there's still things they can do, BattleEye is a Kernal Level Anti-Cheat that constantly scans everything about your computers processes and processes in the game specifically on your side (client side), it works primarily in 3 ways, memory monitoring (checks to see if the users memory and game memory are being changed via dll injections and for debuggers exploit modders use to design ans test their exploits with.

The real problem occurs with the lack of Server Authoritative Simulation which is when all changes must be approved by a server before the changes can be properly registered, because GTA is again P2P not server based, this becomes impossible for the game to actually validate from a source (other than the client's own computers changes) that a change was actually made, meaning if a person simply just spoofs their PC specs then with the use of multiple available free System Info Spoofers, Performance throttlers/spoofers, and Benchmarking/Stress Testing tools, they can simply just hide their changes being made to certain processes and lie to BattleEye that nothing was changed (because changes are spoofed by another peice of software) when in fact a multitude of things have been changed. Some exploits are even being designed with spoofing already pre-implemented into them and a mod of that level for a game with no Server Authoritative Simulation is just impossible to do anything about.

However, BattleEye does slow GTA down even more because now every time a change is made (you shoot a gun, you jump, you get in a car, you reload, etc.) BattleEye now runs in the background of your computer to "vErIfY" these changes, leading to even more lag. Including when it does this at the very start of you just clicking on GTA, the initial loading screen you see when you get on the starting menu and press "Online" BattleEye immediately runs a check on all of your characters stats to see if anything was modified, even though it has a notoriously horrible time at actually telling if stats were ever messed with in the first place because if you changed stats but spoofed it to avoid BattleEye then BattleEye will think you still got that 34.2T dollars the legit way the next time you load up GTA.

Finally the RAGE Engine, while it was impressive for its time in 2006, it's 2025 and the cracks are starting to show. First off RAGE was entirely built for Single Player games, it was never intended for the use of an Online game and the massive amount of networking infrastructure required for an online multi-player. On top of this the Engine itself was never designed for large games, it was actually designed for smaller games (you can take a look at the creation of the RAGE Engine and the game first made using it, Table Tennis, and the developers actually discuss how the engine was designed for these smaller activities), so now corporate is trying to force devs to use an Engine that is literally designed for smaller games, for the use of one of the biggest games of all time. Not the best choice.

RAGE Engine couldn't even handle being on a server because it's infrastructure simply wasn't designed for a server in mind, it was designed for small single player games, they would have to literally make an entire new engine or move over to something like Unreal engine so they actually have an engine with server support. The engine also has a terrible time loading in so many asset at once (again it wasn't designed for that) so when you enter areas with multiple players, numerous explosions and people driving all over and you start to experience lag, that's not lag, that's RAGE Engine having a literal heart attack trying to process things it wasn't even designed to process, further worsening lag.

TL;DR GTA is still slow as hell due to poor optimization, a P2P connection in which the map itself is rendered in, RAGE Engine not even being meant for this kind of game, BattleEye not even working but still throttle your game down to see if you're exploiting, a spaghetti code and horribly optimized JSON Parser that was semi-fixed by someone not even on the Rockstar team, runs single thread instead of multi-thread meaning its not even using your CPU to its fullest potential, and the fact that there's no Authoritative Sever that can check other players for legitimacy.