Although some people have blamed it on the HTML 5 and the animations, that is not the reason for this unusual behavior.
However there is a fix for this problems and just follow the following steps for a lag free experience:
- Open settings, go to privacy, and then go to location services.
- Scroll down and open up system services.
- You will find “Genius for Apps” simply turn off this feature.
The genius for apps settings always has this grey or purple icon next to it, which shows that it has been using location services. Turn this off and the sluggish experience suddenly disappears. This is because the so called Genius uses GPS and does that in the background and hence slows down the phone.
Once you turn off this option, double tap the home button and close the App store re-launch it and you will find everything runs smoothly.