Migration Assistant Very slow

16 hrs later the migration assistant seems to be still on the job without giving any indication how far it has progressed and how much time is required to complete the transfer of information from an old Macbook pro (mid-2012) to new Macbook pro 2021. Cable used is USB (connected to old macbook pro) and USB-C (connected to the new Macbook pro). The machines call it ethernet connection with a data transfer speed of 39 Mb/sec. Old HDD size is 500 Gb with around 450 Gb data.

Any one dealt with similar challenge experienced? What happens if i cancel it midway?