SharePoint Online - Performance tweaks to improve import process?

Hi,

Has anyone got any tips on improving the import performance of data into SharePoint for larger than 20Gb data sets?  I use a PowerShell script to do the upload process which useses the https://support.office.com/en-us/article/Upload-on-premises-content-to-SharePoint-Online-555049c6-15ef-45a6-9a1f-a1ef673b867c?ui=en-US&rs=en-US&ad=US cmdlet to do the upload into Azure staging which is then imported into SharePoint.  I've been using the same scripts for ODfB with no issues, but with less data.  However the SharePoint team site import process is really really slow, for example it has been running for over 12 hours now and I only have half the content showing in the document library it's importing into.  I am using the - parallelimport switch to try and speed up the process.

Any feedback/hints/tips would be really useful.

Thanks

Rob