Everytime that you open your project's history Mendix Studio retrieves the history from the Team-server. This takes seconds and the more history there is to retrieve, the longer it takes.
The history-data itself is static. Once a history line is added to the history, it never changes anymore. So:
Store the history-data locally and only retrieve the history's delta.
This saves waiting time for developers, and reduces load on the Mendix Teamserver.