The textures have nothing to do with saves. Installing or removing the hd textures shouldn't effect the actual game in any way, other than the texture quality.
That being said, the hd textures are slightly more demanding on your system than just the default game and the game is already pretty demanding, and especially on your cpu. I personally would make sure the game runs well before you install the hd textures. It won't effect your save file if you want to start using them after your initial testing.
That being said, the hd textures are slightly more demanding on your system than just the default game and the game is already pretty demanding, and especially on your cpu. I personally would make sure the game runs well before you install the hd textures. It won't effect your save file if you want to start using them after your initial testing.