Grand Theft Auto 5 will be hitting next (or current... this transitional period is always confusing!) generation consoles natively in 2021, with special ports loaded up with all kinds of enhancements that make the most of the new beefy hardware available. You don't have to wait until then to enjoy some improvements offered by the Xbox Series X thanks to backwards compatibility — someone checked out how much of a difference an SSD makes.
Gameriot uploaded a video timing how long it takes for you to actually start playing after launching GTA 5 on an Xbox Series X console. They timed both Single Player and Online, and the results are interesting — and they demand some explanation to clear up any potential confusion.
From the moment you launch the game, it takes 37 seconds to actually gain control of a character. This is pretty impressive in and of itself, but 32 seconds of that is taken up by the unskippable logos and legalese that hog the screen initially — this is the same regardless of hardware, so everyone will have to sit through it.
However, actual loading time is a mere 5 seconds.
This means that when you need to load into the game for any reason when you're not booting up the game, you'll only be idling around for 5 seconds if you are playing on an Xbox Series X. That's practically nothing, and a huge improvement over loading times on any device running a HDD. You'd assume the same rings true when trying to load into an Online session, but things aren't so rosy.