Just found that with every touch, I am adding 8 new sprites to the layer, and its adding every time I touch . So with time I am giving more and more work to do. This is the problem
Actually I wanted to replace the sprite at 8 places with a touch, the way I was doing every time :-
_colorBottom1=CCSprite::createWithSpriteFrameName(png[0]);
this->addChild(_colorBottom1,kForeground);
_colorBottom1->setPosition(ccp((_colorPanelLeftPad)*_blockWidth,_blockWidth));
It was causing this sprite to be added with every touch.
but it should have been (Replace the texture instead of creating the Sprite again):-
CCSpriteFrame *frame1=CCSpriteFrameCache::sharedSpriteFrameCache()->spriteFrameByName(png0);
_colorBottom1->setDisplayFrame(frame1);