Moving to C++ is an option I considered. However, currently, I do not have to use explicit loops because the NumPy data is directly passed to VTK (both for the creation of vtkPoints and for vtkCellArray). Since I do not implement custom algorithms where the Python layer would be slow, I do not see the urge to move to C++. What I fail to find in VTK (if it is possible at all) is whether it can construct a vtkCellArray from non-contiguous memory addresses. If this functionality exists, but is not exposed to Python, I am ready to turn to C++. However, if this feature does not exist in C++ either, there is no gain to port my code from Python to C++.