Another, much more performance-saving, way is to apply the Voronoi Fracture algorithm directly in the 3D program. This allows you to divide the mesh first and then optimize the pieces again.
(But be careful to not optimizing mesh before destruction, e.g. by deleting polygons! You need the closed mesh here also)
Then you no longer uses the destructible mesh function of UE4, but instead simply swaps the mesh with the help of a blueprint.
This does not take much longer in the “manufacturing” of the destructed mesh, but you have much more control over the mesh and can optimize it far better for a better performance.