iphone - UIImage in uitableViewcell slowdowns scrolling table -

i loading image data in table view. images coming web. created method image url in model class.model class has nsdictionary , objects. images slowing down scrolling .here code

uiimage *image = [uiimage imagewithdata:[nsdata datawithcontentsofurl:[nsurl urlwithstring:[nsstring stringwithformat:@"%@",                                                                                         [(tweet *)[recenttweets objectatindex:indexpath.row]urlstring]]]]]; cell.imageview.image = image; 

please tell going wrong?

use lazy loading , do own drawing. try understand techniques on sample projects linked. these best ways improve performance of tables images.