Rockstar Themselves Said For Best Performance To Play It Off The Disc, Cant Imagine They Have A Hidden Agenda Against Installing It On The Drive But Hey, Whatever 
you still aint listening. of course rockstar would say play it off of the disc. lets go over this again.
for xbox gta 5's. you have 2 discs.
disc 1 (install disc-has to be installed on your xbox hard drive OR you could have installed it on a flash drive)
disc 2(game play disc- this is the disc you have to leave in your xbox the entire time you play the game.)
now using it like the above setup. no issues. EXCEPT for a slight degrade in graphics but you wont notice until you watch that video or you yourself have played it off the disc then tried the usb version as well.
moving on..
some people THOUGHT, "hey..what if i install disc 2, into my xbox hard drive so my DVD player wont have to run all game long and it should run faster like all other games."
^^you might ask, why would someone do that? because all xbox games run faster when you install the full game on your hard drive. this is the first time it actually runs worse. that has to do with something rockstar did to the programming and the way it accesses information in different places. i'll give you an example. LA noire had multiple discs. i installed them all on my hard drive. including the main disc that has to sit in the console why you play. it made the game play smoother. zero hiccups, glitches or graphical issues. this is why people assumed the same would or could apply to gta 5. but thats obviously not the case now since we know they did something different with the programming of this game where that doesnt work like it use to.
So now you have the choice play it off of the disc. or install that "main player disc" on a USB drive since the rest of the game is on your hard drive. that would work even better then it being on the DISC. because the USB read speed is FASTER then the DVD drive's speed. which means where your dvd at some point may show you a slight lower grade in graphics or hiccups the more /longer you play. the USB method wont have ANY issues at all, ever(unless your usb flash drive has problems. but thats rare.
basically the install the "install disc" on the hard drive. and install the "game disc" on a fast usb flash drive = OPTIMAL PERFORMANCE.me personally. i would rather not have my DVD spinning around for hours every time i play this game. it makes the entire box hot. in addition the more it spins the less amt of spins you have(every drive has a life span aka X amt of spins before it goes out. you never know when your time is up. remember most of these consoles are OLD. and depending on how much gaming you do, dust in your house, etc. no telling. why risk it? is my point.
NOw you know. do what you will with the info.go ahead and play it off of the disc and pray nothing ever goes wrong. odds are nothing will go wrong. but i like to get rid of those odds altogether. thats just me.
**last thing. again of course rockstar will tell you for best performance install the install disc on the hard drive and leave the main disc in the console and play that off of the DVD drive. they wouldnt mention that it would be even better if you installed the game disc on the USB drive(while leaving the disc in the console-but it wont have to spin anymore). the reason why they would not mention this is because that would FORCE people that even have the hard drive space to go out and buy an additional piece of equipment(flash drive). they dont want to hear that backlash. so they let you know the default way to play the game. not the most optimal.
and runs perfectly fine, but i'm gonna try this and see's if there's any big difference, though the noise my 360 is making is
.
