Happening with me also. First two pictures load. To view all pictures I click on the picture to open in dialog and then click on black area where a picture could be as a thumbnail and then it loads up. But on the page itself it never loads more than 2.
I tried with different browsers and different internet connections but no success. Didn't bother to complaint because I once complaint pakwheels about the load time of their website but no one was bothered. Though I am not a big fan of olx but load time of an ad on olx is still less than pakwheels.