420MB mailbox move from 2010 to 2013 took an hour to complete. Very slow.

The same size mailbox moved to another database on another 2010 server took only 13 minutes??

Hi Andy,

I would like to confirm from you some queries like which process you are following (Manual Mailbox Migration or any automated tool process)? You are doing stage migration or cutover migration? Please confirm so that i can help your further.

Walter

Manually using New Local Mailbox Move. Staged migration.

Hi,

This issue may be caused by more factors, for example disk speed, network latency, mailbox folder structure and index.
You can refer to Nikos suggestion in below link: https://social.technet.microsoft.com/Forums/office/en-US/ae9f2630-393b-44b0-a805-774e571906f1/mailbox-migration-exchange-2010-to-2013-very-slow?forum=exchangesvrdeploy

Besides, open MSExchangeMailboxReplication.exe.config(locate in <Exchange Installation Path>\Program Files\Microsoft\Exchange Server\V14\Bin) and try to change the value of MaxActiveMovesPerTargetServer. The default value is "5".
For your reference: https://technet.microsoft.com/en-us/library/ff963524(v=exchg.141).aspx

Thanks

While performing mailbox migration, there are many possible factors which could be responsible for your slow migration speed such as your Protocol connectivity, content index error, your enabled TCP Chimney ,etc. You can find few steps here which may help you to increase the speed of mailbox migration:   https://rajisubramanian.wordpress.com/2014/05/30/slow-mailbox-movement-on-exchange-2013-sp1-mailbox-migration/ 

If you want do quick, error free migration from old Exchange 2010 to Exchange 2013 Server , then you should try an automated tool. I would like to recommend you one of the tested solution by myself Stellar EDB to PST converter which provides you hassle free migration without causing you any downtime.