Performance slow issue of mail migration to office 365 in hcw 2013

Our customer have experienced slow mailbox migration issue in HCW 2013, when we take a test one mailbox migration that size is 25MB, it takes so long than we expected about 45mins.

If I run Get-MoveRequest | Get-MoveRequestStatistics , CopyingMessages status details takes 40 mins, do you have any ways to check mailbox migration to office 365 from on-prem server in hybrid structure?