Dear Deba and Kai,
thank you for your suggestions. Deativating Sophpos did actually
speed up Octave marginally.
Please remember to bottom post on this mailing list.
I know on my windows installation I (intermittently, randomly) have to wait 10-30 seconds for the GUI to open. I also sometimes have long delays after a CD to a folder with a large number of files, I think waiting for the file browser window to update. Sometimes while it's hanging I jump into the task manager and the "Analyze Wait Chain' function usually says it's waiting on network activity. It's a managed windows system so I don't have freedom to disable the background utilities, and I always assume I'm waiting on part of the security suite to check in with home. You can always check that and see if some process or service pops up in the wait chain. Event Viewer or Resource monitor are also behind admin blocks, so I can't peek at those, but they could give hints as to what's happening.
Did you mention that this is new with v5.2.0? Have you tried reinstalling an old version to see if the problem persists?