When changing something that would cause an update to a lot of projects then Qt Creator can hang for some time while it is reacting to the change.

Changes like changing a common pri file (that is included in a lot of projects) or checking out a new git branch which means a lot of files in different projects would be changing can cause Qt Creator to hang for sometime while it updates as a result of the change. Ideally, this would be done in the background as much as possible as it can end up hanging for minutes if there is a lot of projects/files involved.