Performance Profiling

# Summary

Performance when loading UI seems to be unacceptable right now.

## Steps To Reproduce

```
1. Create a new Xcode project.
2. Integrate MBCalendarKit 
3. Create a `CalanderView`
4. Profile
```

## Expected Results

Calendar view should display quickly.

## Actual Results

Instruments shows that several methods take way too long (>500ms) to run.

## Notes


