Map Maker will handle fairly large data sets, but there are a instances when it has a tendency to hang.
Too many layers
If you are working with many layers, try clearing any layers you do not need. Try also using the drop-in drop out functions, to show layers at the appropriate map scale.
When you try to load a big .shp file the timer never stops, OS Master Map for example.
We have created a .dra of OS Master Map which seems to overcome the hanging problems.
To create a .dra from a .shp use the UTILITIES > VECTOR menus to import the file and save it as .dra