Patrick- On the netcdf-3 vs netcdf-4 issue I can at the moment only speculate. As a rule, reading small quantities of data with netcdf-4 is always slower than netcdf-3 because the underlying HDF5 file format is based on b-trees rather than the linear disk layout of netcdf-3. Since vars reads a single element at a time, that overhead can, I suspect, be significant. I am, however surprised that it is as large as you show. =Dennis Heimbigner Unidata =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: ZFB-587742 Department: Support netCDF Priority: Normal Status: Closed