As far as i know not. In MxID we solved this issue by using an intermediate step: 'click here to confirm'. But probably this solution is not applicable in your case.
It needs to synchronize a lot of user data with a back-end system over webservices. We do this on login to ensure the info is up to date. Doing this update periodically (saving time on login) would increase the risk that the info is incorrect
Why don't you synchronize just before opening the corresponding form? It provides a better user experience, the delay is related to what you are actually doing and i guess it reduces the number of (unnecessary) syncs. I can imagine though that this approach becomes nasty when you use the data in many different views or MFs.
Maybe you should change your login microflow. Why does it take so long?