When I update a setting the first time it is fast (1/10 second). If I update it again right after, it is very slow ~ 3 or 4 seconds. If I keep updating it (keep clicking a button 'update test') it runs slow, ~3 or 4 seconds each click. If I then navigate away from the test page to a page on the same website, that navigation is slow, ~3-4 seconds. After that everything is fast again. If I go back to the test page again, the first time I hit 'update test' it is fast. After that it is slow again.

 The reads are always very fast, it's just the writing that seems to slow everything down.

Is there something I should know about PortalSettings performance? Has this to do with caching? What am I missing?

 Public Shared Property myProp(PortalId As Integer) As String
        Get
            Return (Portals.PortalController.GetPortalSetting(PortalSettingsPreFix & "myProp", PortalId, ""))
        End Get
        Set(value As String)
            Portals.PortalController.UpdatePortalSetting(PortalId, PortalSettingsPreFix & "myProp", value)
        End Set
    End Property