Lossless simplification?

[Badfitz]

I have a 3D tile based map editor tool that I use to quickly create stuff for my game (building interiors, etc). At the start of runtime, I have to merge all these tiles into one big mesh because otherwise there's a huge performance drop (thousands+ of tiles. Static batching doesn't really help either, especially with post-processing is also on). This mesh, however has a lot of triangles that don't really need to be there, causing the mesh to have a lot more triangles than it needs.

The solution I feel that would be best for this is some sort of variant(?) of the Greedy Mesh algorithm made to work on arbitrary meshes instead of voxels (Greedy Meshing is mostly/solely used in minecraft-esque games).