creating a vector container

Hi, I am new to everything step forum and snap.
Was trying to do supervised classification and every thing is fine but writing to the file in creating the vector container takes ages, any help, thanks in advance.
Gar alnabi

I’m not sure if I understood you correctly, but if you imported an original file, add a vector container, and then save the product, SNAP stores the whole product as a new file first (including all rasters) in BEAM DIMAP format. This could be a reason for the time. Because SNAP cannot store vectors in original files or GeoTiffs. What data are you using by the way?
So if you don’t need the entire image area, it could be favourable to create a subset first and afterwards add the vector container directly in the subset (saved as BEAM DIMAP).