DROP USER takes too long when there are many users

On a SQL Server 2014 instance with enough RAM and fast disks, there are over 160 users that have access to a database. For some reason unbeknownst to me, running the command DROP USER [username] in this database takes up to 5 seconds per user.

Remapping users to logins and restoring their permissions is very fast.

Within the context of refreshing DEV databases from production, I have to drop and recreate all database users. So yes dropping the database users and recreating them is necessary.
How do I speed up the DROP USER command?

Remember, I have to run it over 160 times for the instance I'm writing about.

This is the SQL I'm using:

DECLARE drop_user_cur CURSOR FOR 
SELECT name FROM #drop_users

OPEN drop_user_cur
FETCH NEXT FROM drop_user_cur INTO @user

WHILE @@FETCH_STATUS = 0
BEGIN
    SET @sql = 'use [' + @db_name + '] DROP USER [' + @user + ']'
    BEGIN TRY
        print @sql
        EXECUTE(@sql)
    END TRY
    BEGIN CATCH
        print 'ERREUR : ' + @sql
    END CATCH
    FETCH NEXT FROM drop_user_cur INTO @user
END

CLOSE drop_user_cur
DEALLOCATE drop_user_cur

The problem is not coming from cursor; it's the actual DROP USER that's taking up to 5 seconds.

Using sp_whoisactive, the wait_type is NULL.

Don't pay attention to the duration, the DROP and CREATE USER were being run in a WHILE loop which is why it's saying more than a minute.

Profiler shows over 125,000 reads to execute DROP USER.

Service Broker is not enabled.

The resolution to this issue was enabling service broker on the database as so.

ALTER DATABASE [Database_name] SET NEW_BROKER WITH ROLLBACK IMMEDIATE;

After enabling service broker for the database, drop users were practically instantaneous.

Kin asked if the service broker was enabled in a previous comment which sent me searching in the right direction.

StackExchange Database Administrators Q#140092, answer score: 6