Import million .vtk files at the same time


I am working on a dynamics simulation, and exporting .vtk files at every time step. However, when I try importing those files at the same time, the program (paraview) lags too much, and it seems impossible to do in this way.

Can you give me some comments on how to import many vtk files?
Do you have any recommendation for a data format other that .vtk?

Thank you.

You may wan to use VTKHDF file format