I have installed Spark 2.6.3 and am using Openfire 3.7.0 on a Win2008 server.
The issue is that sending messages to one of my contacts is seriously delayed where other contacts are not.
It is only a 1-second delay, but it is really annoying.
I suspect it is client specific because I have logged in from another computer and the problem is not there.
I once clicked on the tranlsation button (even though this wasn’t required) and I wonder if this has something to do with it.
You type a message to the contact in a new window and there is a 1-second delay between hitting enter and the message appearing in the conversation (and the contact receiving it).
I have tried uninstalling the application but I can’t find all the residual config files so that the install is truly clean (which I presume would fix the issue).