Message imports with the message connector seem to need longer than expected.
It could be that the default ingest time in KTA might give you the impression that the import is slow.
The default ingest time is set to 1 minute. To change that, try the setting with 0 minutes.
In the KTA Designer, click on “System Settings” and this screen will appear:
In “System Tasks”, set the “Ingest” task to 0 minutes (default is 1):
Level of Complexity