VTK export specifies binary format but writes ASCII files
I noticed the vtk files written by openfoam are quite large - by reading and re-writing from paraview they can be made half the size.
This is easy to reproduce, just run the following on the motorbike tutorial.
postProcess -funcs '(expCl_isoP expCl_wallVtp)'
It would be useful to have binary, compressed files as the files can get quite large for unsteady runs. Reporting as a bug since the source code and documentation suggest this capability is intended to be there already.