We are unable to reproduce the 'freezing' issue on a Samsung S4 with android version 4.4. However, i am able to see the slow performance which is due to the heavy graphics in the file. Would it be possible for you to make a small video of the issue you are observing?
Nice to see that you're testing. : )
By freezing I meant that the app freezes while it tries to zoom for about 10 seconds then it resumes operation but it's very slow and can't navigate the zoomed file and also does not zoom to the max level.
Yes, the graphics are heavy but 1-2 other apps (popular) on the Play Store zoom with ease and your app is the worlds default PDF app (at least in my opinion).
Hope it helps.
We have made a note of your issue and shall try to fix it soon.