STMS delay of 5 minutes

Hi

I work on many sites, but for the first time I encounter an issue with STMS at one of my new clients. It seems like the transaction has a setting that delays the import of the transport with 5 minutes. On most sites it's done completed within 10 - 15 seconds. So the 5 minute delay is very annoying and I can't figure out where and how to change this? The client is still on 4.7. Is this a scheduled batch job where we can change the frequency?

Please assist.

Thanks, Adrian