Problem of blurred image when zooming on second screen LR 5.2 and 5.3RC

I just installed Lightroom 5.3 RC to check whether a specific problem had been addressed or not: it is not.
Problem: on a system with two screens, when in the Develop module, zooming into a picture on the second screen does not give a sharp image. Same zoom on the main screen shows a sharp image. The problem happens often on my system but may be less frequent on other systems.