Getting the initial sync set-up between NetSuite and HubSpot can take hours or days (depending on the volume of data e.g. thousands or hundreds of thousands of records). We'd recommend giving yourself a few days to run the initial sync/import if you have a lot of records.
However, once you're integrated and in maintenance mode we'd expect sync times to be a few minutes or instant. If that's not what you're experiencing, I'd recommend contacting HubSpot support and asking them to look into what might be causing delays.