If I run the convert-spwebapplication cmdlet I can see in the ULS logs that the SharePoint conversion process completes in around 30 mins. The Nintex stored procedure is then automatically run and that takes anything up to 12 hours to migrate the same set of users. I can see in SQL Profiler the MigrateUserInContentDB stored procedure running for hour after hour. Neither the SQL server nor the SharePoint server show any sign of performing poorly in any other regard. The farm has around 500GB of data split between 10 content databases and something like 15k unique logons over the course of a year. Most of those are not regular users but I can see there could be a lot of records to update. Does the sort of time I'm seeing for the conversion seem right? Are there ways to speed it up?