ios - Objective C: UITableView Scrolling becomes Laggy -

i have uitableview becomes laggy when during scrolling. code snippet follows:

in "cell setupcell" have few customized items added cell contentview

• 1 x uiimageview

• 3 x uilabels

• 3 x buttons (subclass of uicontrol)

my initial testing seems point buttons causing lag. have checks in button class

i not sure cause lag these checks seemed simple , basic operations. has advise on causes such lags?

edit: add more code

i want add scrolling smooth when first started app, became laggy , slow after scrolled table , down multiple times. code follows:

if (cell == nil) {     cell = [[[customcell alloc] initwithstyle:uitableviewcellstylesubtitle reuseidentifier:placeholdercellidentifier] autorelease];     //add button     uicustombutton *likebutton = [[uicustombutton alloc]init];     likebutton.tag = 7;      //add comment button     uicustombutton *commentbutton = [[uicustombutton alloc]init];     commentbutton.tag = 8;      //add answer button     uicustombutton *answerbutton = [[uicustombutton alloc]init];     answerbutton.tag = 9;      [self.contentview addsubview:likebutton];     [self.contentview addsubview:commentbutton];     [self.contentview addsubview:answerbutton];      [likebutton release];     [commentbutton release];     [answerbutton release]; }   //set button uicustombutton *thislikebutton = (uicustombutton *)[self.contentview viewwithtag:7]; [thislikebutton setbuttonwithanswer:self.answerforcell buttontype:@"like" navcon:self.navcon andframe:cgrectmake(cell_text_left_margin, totalcommentlabelheight + cell_spacing*4, 45, cell_button_height)]; thislikebutton.imageview.image = [uiimage imagenamed:@"heart.png"];   //set comment button uicustombutton *thiscommentbutton = (uicustombutton *)[self.contentview viewwithtag:8];  [thiscommentbutton setbuttonwithanswer:self.answerforcell buttontype:@"comment" navcon:self.navcon andframe:cgrectmake(cell_text_left_margin + 45 + 5, totalcommentlabelheight + cell_spacing*4, 80, cell_button_height)]; thiscommentbutton.imageview.image = [uiimage imagenamed:@"chat.png"];  //set answer button uicustombutton *thisanswerbutton = (uicustombutton *)[self.contentview viewwithtag:9];     [thisanswerbutton setbuttonwithanswer:self.answerforcell buttontype:@"join in" navcon:self.navcon andframe:cgrectmake(1.5*cell_text_left_margin + 45 + 5 + 80 + 5, totalcommentlabelheight + cell_spacing*4, 60, cell_button_height)]; thisanswerbutton.imageview.image = [uiimage imagenamed:@"beer-mug_white.png"]; 

i have checked instruments , don't seem indicate leakages part of code

can advise might cause of laggy after series of scrolling?

run in instruments, see it's spending time when scroll.