You can invoke the Proxy Geometry tool from Blueprint and Python scripts. This can help you automate your Asset creation and data preparation pipeline, combining and simplifying Static Mesh Actors and their Materials from scripts that you run inside the Unreal Editor. This can significantly improve rendering performance at the cost of some visual precision.
For example, this wheel assembly contains 147 separate Static Mesh Actors with a total of 900,000 triangles, with a separate Material for each mesh. This adds up to hundreds of heavy drawcalls on the GPU. After running the Proxy Geometry tool, the Actors are merged into a single model with a single Material, which can be rendered with one drawcall.