[Paraview] RAM friendly file format?

[noelieboy at online.ie]

Hi there,
I am currently writing legacy VTK files of a surface made 
unstructured_grid using fortran 90, and look at them  in Paraview that 
is installed on my desktop PC (2GB RAM). I now want to start viewing 
large models and using the current method the files are getting big and 
also paraview crashes (i assume due to lack of RAM). Is there any 
particular file format (xml/ensight etc) that is designed to use less 
system ram when visualising the models, for the same model detail? And 
as a second question, which one would be the recommended format for 
generation using fortran90 ?