LOD or level of distance for 3D models/voxels

[Darkcrafter]

As the amount of mods and levels containing 3D models and voxels increases there may be need of some optimization. One of them is level of distance.

A 3D model of a thing may have huge amount of polygons when it's close to the player and get dramatically reduced as it gets farther from it thus speeding up the game in big and especially open maps like slaughter, forests, deserts, landscapes and hellscapes.

How is it supposed to be done if possible, will there be a need to specify lod levels in modeldef for each model number or will it be done by giving it a special prefix or ending? I don't know but to me it feels like the computational savings will get massive.

Will we have to make the level of details on our own or gzdoom could trim the models down to desirable amount like 3ds max "multires" modifier is capable of doing without screwing UVs too much.
Will there be still a way to make our own models made carefully for each of the desired levels of detailisation?

Let's say it's a big slaugther map with cheello voxel doom pack and how big the performance gain will be with lods, hmm... won't it lag while actor models get swapped from one level of detail to another?