We recently got this question as a support issue and tracked this down to the user settings that Paratext backs up about once a week on the Send/Receive server.
This is done so that when a user installs Paratext on a new machine, their user settings can be retrieved from the server and make setting up the new computer easier.
Normally the settings are pretty small and most users probably don't even notice when the settings are sent, but the user sending the report had some large files in the settings, so sending these was taking a significant amount of time.
If you are noticing a large settings file being sent to the server after the send/receive completes, it is OK to cancel this. You may also want to track down the source of the large settings. You can look at the C:\My Paratext 9 Projects\UserSettings_{userName}\Settings to see what is being sent. This folder contains copies of data from other locations, so you would want to delete any files you don't want to send both from the UserSettings folder and the original location.
We are making a change to skip files larger that 2M and to skip sending the settings when the total compressed size is over 10M. This change will be in Paratext 9.4.
