@AvonDM 

QuickBooks data files larger than 500MB need to be optimized every 6-12 months to ensure they run at top performance. There is no internal functionality in QuickBooks to optimize the data file other than running a condense. The optimize operation will copy all data into a new data file, remove unwanted temporary data, and audit trail data to bring down file size by 25-40%. This will improve the performance and stability of the data file.

If you consider migrating a data file with more than 750K Total Targets to  QBO Advanced, you need to purchase a 3rd party service.