Mailbox migration between two Exchange 2013 servers is horribly slow

Hi,

when migrating mailbox between 2 exchange 2013 servers,it s horribly slow. I have found some articles which describing problems about content indexing and missing AD group. This is not my problem, I have tried solutions but it didn't work. Both exchange are next to each one, same VLAN, same switch. Just migrating between databases.

When I start batch jobs it is migrating only 1 mailbox at once and speed is really slow (2000 - 3000 mail items per 5 minutes). So mailboxes which have 10GB it's migrating 3 hours. My server is on 1gbps LAN.

I have also checked MsExchangeMailboxReplication.exe.config on both servers:

    MaxActiveMovesPerSourceMDB="20"
    MaxActiveMovesPerTargetMDB="20"
    MaxActiveMovesPerSourceServer="100"
    MaxActiveMovesPerTargetServer="100"
    MaxTotalRequestsPerMRS="100"

Do you have any idea where to look why only 1 mailbox is migrating at once?

Thanks