Galera cluster replication stalls when using wsrep_provider_options repl.commit_order=2
(Is your question mostly about the "migration"?  Or about write performance on the resulting Cluster?)

Look at your transactions.  Optimal is some sort of "medium" size.  Too short leads to long latency.  Too long leads to extra risk of deadlocks/failure at COMMIT time.

Look at the network.  You are dependent on how far apart the nodes are.  If there are next to each other, you do not get the HA benefits.  If they are too far apart, you have latency issues.

Look at the write queries.  If they are likely to conflict, but you are sending them to different nodes, then you may be adding to the problem, relative to somehow focusing some sets of queries onto a single node.

Do you have "critical reads"?  How are you handling them?

More Galera tips .