Proper detail streaming requires a specific install configuration.
In order to save wear on the disk drive as well as keep the noise level down and prevent disc reading errors, the Xbox 360 offers the option to install data from any 360 game disc. In the case of 'Grand Theft Auto V' though, this optional install looks to be causing some issues.
From Rockstar, "For optimal performance, we recommend not installing that (the play) disc. We will have more info on our Support Site at launch."
360 version of 'GTA V' has an install disc and a play disc. It is the the optional install of the play disc, done through the 360 dashboard interface that is causing the issue.
Digital Foundry has put together a video comparing the differences between 360 version, one with the play disc installed and one without.
While installing a 360 disc is normally a sound choice, in the case of 'GTA V' it seems that the game needs the hard disk bandwidth for accessing the 8GB of mandatory install data, while using the disc drive's bandwidth in order to load in the full detail of the game's environment as quickly as possible.
You can find the latest info on 'Grand Theft Auto V' linked from our Video Games Release Schedule.
Author: Brian Hoss