Created attachment 54538 [details]
When document is zoomed, characters get distorted (see attachment).
It seems that the bug is related to the size of the character on the screen (smaller fonts can be zoomed more before the bug occures).
The same behavior can be reproduced also in older versions (also e.g. OOo 3.2.1).
Thanks for bugreport
Looks like problem with video driver
Please, try on another computer with different video card and tell result
Seems to be NVIDIA prop driver bug. OK with Nouveau.