Your font has lost its hinting:
Use the method described in This Tutorial Thread
To scale a font down from 14 pt to 13 pt
- Edit, Select Composites
- Edit, Invert Selection
- Format, Settings, Header, and set funits/em to 2206 (2048*14/13) (assuming it is now 2048)
- Edit, Copy
- Format, Settings, Header, and set funits/em back to 2048
- Edit, Paste
Be mindful that modifying Microsoft fonts is not permitted. Do not redistribute it to anyone.