MuseScore Freezes When Opening A File

After I told MuseScore to open a file, the program froze and my mouse became completely unresponsive until the score finished opening.

To be more objective about it, I've attached a screen recording. At the 00:00:20.574 mark, I clicked the "Open" button. The score is displayed at the 00:00:22.624 mark. 2.05 seconds passed.

According to http://www.nngroup.com/articles/response-times-3-important-limits/, 0.1 seconds is the limit for feeling like the computer is reacting instantaneously and exceeding 1.0 seconds will interrupt the "user's flow of thought".

Details:

- MuseScore nightly build (da1a230)
- Windows 7 SP1 x64 (English, United States)
- Solid state disk
- 8 GB RAM
- Intel Core 2 Duo P8700