Taken from the tweak guide I shared earlier
uGridsToLoad=5 - This variable does not exist and need to be added to bottom of the [General] section of the Skyrim.ini file to be implemented. It controls the radius around the character within which the engine loads up the most detailed objects, characters and terrain. It can have a substantial impact on both image quality and performance. Any value assigned to this variable needs to be in odd increments, e.g. 3, 5, 7, 9, 11. The screenshot comparisons above demonstrate the way in which there is progressively higher detail in the distance as the value of this variable is raised (a better example showing uGridsToLoad=7, the most stable value, can be seen here)