I had those problems for a while with gt6. Some textures wouldn't load until you were almost right on top of them, buildings popped up a few metres ahead, and sometimes stuff just wouldn't load at all. At the time it was pretty much the only game I played, and when it would start playing up like that, the ps3 would make funny noises, like it was struggling to load the disc. Eventually the laser burned out and the console wouldn't play anything.
I replaced the laser, and all discs loaded perfectly, but kept having load issues with gt6. Game would load up fine, but lots of this texture disappearing and lots of crashes and 3 beep shutdowns. Eventually it killed the ps3, I think all the hard crashes just ruined the system, as it wasn't the laser the last time, the system just struggled doing anything. Would even crash when trying to load an external hdd or the ps store. All of this started after a certain update, I forget which one. Might have been 1.16.
Never had any trouble with any other game or disc, and the ps3 was well looked after, regularly cleaned out, kept well ventilated, and never in a smokey room (I'm a non-smoker), so I'm convinced gt6 killed it. Was the only game that seemed to stress the system out. Constant loading noises and fan going nuts all the time. Updates only made the game harder on the system.