GTA5/online is based on one of the most sophisticated and highest performance gaming engines developed at the time (the RAGE engine).
The infamous loading bug [1] is something that only happened on the PC release of GTA5, which among all platforms was the least popular and came out two years after the console release.
Given how many modern games have downright failed due to performance issues/frame rate issues plaguing the game on release, I can assure you that had GTA5 released with significant performance issues it's quite likely that the reviews for the game would have bombed and it would have sold considerably less than it did.
The infamous loading bug [1] is something that only happened on the PC release of GTA5, which among all platforms was the least popular and came out two years after the console release.
Given how many modern games have downright failed due to performance issues/frame rate issues plaguing the game on release, I can assure you that had GTA5 released with significant performance issues it's quite likely that the reviews for the game would have bombed and it would have sold considerably less than it did.
[1] https://nee.lv/2021/02/28/How-I-cut-GTA-Online-loading-times...