Hi Richard,
Generally if you notice any slow operations you should see something similar written to the stdlog:
The following statement took xxxxx milliseconds
If you are noticing these messages at the time of updating a workflow the document below describes methods to diagnose and resolve these types of issues.
CA Service Desk Manager (Service Desk) and MS SQL - CA Knowledge
Also hitting the refresh workflow button is a separate process and will not slow the update down, however if the SQL update is still running in the background then you may not notice any difference.
Thanks,
Scott