LOD
Level of Detail (LOD) is the principle of having lower-detail versions of models in memory and switching to them when the object is small/distant. This saves a lot of unneeded processing power at the cost of a moderate memory/disk size increase.
Model LODs change instantly. Be careful that your LODs do not create visual noise when changing, it can be distracting. An example of this can be seen on some tree props in Water Hazard.
Warning: Counter-Strike: Global Offensive does not support LODs at all, or it is possibly broken due to updates[confirm].
See also
- LOD Models, a good tutorial on making LODs
$lod
- MIP Mapping, the texture equivalent of LODs
func_lod
, a brush entity (fades out, not really LOD)