Characters come and go, but History remembers them.
Until there are too many and it locks up.

Solution:
Delete your old scrap characters.

Go to the savedvariables folder and copy the history.lua file somewhere safe.
The script makes a backup into a subfolder History_bak. You can totally trust that, Right?!  Nope.


Start the iuplua53.exe  console
Use the "Load" button, navigate to the history folder and select  Delete-Character.lua
Click Execute.

If there is more than one account in use, select the account.

Make the dialog wider, because I can't be arsed figuring out how to do it under program control.

Select a Character to be deleted.
Confirm.

Click "Execute" again to delete another char and repeat.

Close the iuplua console when finished.