You should check whether the problem is in the complexity of the final mesh, or in the cost of adding a new cutout if there are many of them (for example, ISM/HISM has a similar “problem”).
If the first, then most likely you will have to combine a large cluster of small cutouts into one large one (and figure out how to do this unnoticeably for the player)
If the second, then the model itself should initially consist of smaller parts, so that it is impossible to create too many cutouts in one part.