Ok i have got the solution..
Actually i am downloading data asynchronously and wanted to load them as part by part..
For that i have scheduled one selector to reloaddata for tableview..(I have set 0.2 time period for it )
schedule( schedule_selector(NewsLayer::refreshData), 0.2);
But lately i have realized that when i am scrolling that time also table is reloading their data as per time period and fps got low..
So i have removed that scheduling and fps issue is solved..
And i will try some different way to load data without affecting performance and also if you know some suggestion for it..