Playing with large files is not a very good idea if you are running a sync service. You can indeed use the PSUtilities to unzip your file but make sure you have enough free memory on your IS to deal with this as if you have multiple files being unzipped at one time the IS can eventually slow down. Best approach would be to have a single thread designed to run in an async way i.e. publishing a doctype from the broker to another service to make the unzip operation independent of the main flow.