When working with a WSUS console if you ever need to look at the Syncronizations it takes a long time to load. This is due to the way the logging functionality was designed which over months or years can cause this pain to minutes to load in some environment. However, this data can be cleaned to provide much faster load times.
If you want to purge the entire Syncronization history:
DELETE FROM tbEventInstance WHERE EventNamespaceID = '2' AND EVENTID IN ('381', '382', '384', '386', '387', '389');
Otherwise if you want to keep the more recent records you could do something like the following:
DELETE FROM tbEventInstance WHERE EventNamespaceID = '2' AND EVENTID IN ('381', '382', '384', '386', '387', '389') AND DATEDIFF(month, TimeAtServer, CURRENT_TIMESTAMP) >= 2;