Splitting a Mesh into Submeshes

I am currently trying to modify meshes in runtime and therefore also updating their colliders at runtime.

Since I am using rather big meshes I was wondering whether it is possible to split an existing mesh (either within Unity or beforehand manually somehow) into multiple submeshes - sorted by “connection” of triangles. This way I could probably achieve a much higher performance since I would not have to modify the “whole” mesh but smaller parts of it.

In Unity 5.6 and older there already was a vertice limit of 65535 which made Unity split the mesh automatically but without paying attention to connected triangles or so and therefore not too useful.

I doubt one could split meshes right inside Unity.
You need to use 3D modeling software to do that. For example, here’s how you could do that in Blender (selecting different parts and making them separated meshes is starting from 6:25): - YouTube

Shouldn’t this answer your question?