Why is my push animation so jerky?

Question

I am in a 2nd level screen, and I want to animate the return to my main screen, but for some reason the animation is jerky, and doesn't go nice and smooth like card flipping animation. the code is:
+ (void) doPush: (id) arg_masterview
direction: (NSString *) arg_direction // e.g. MOVINGLEFT,VINGRIGHT
duration: (float) arg_duration { // e.g. TIME_TRANSITIONS
// Set up the animation and fire it off
CATransition *animation = [CATransition animation];
[animation setDelegate:self];
[animation setDuration: arg_duration];
[animation setType: kCATransitionPush];
[animation setSubtype: arg_direction];
[animation setTimingFunction: [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
[[arg_masterview layer] addAnimation: animation forKey: @"KEY_doPush"];
anyway it moves jerkly like, consistently and yet I am not doing anything in the background with other threads, etc.

Answer 1

I hope you don't mind me asking you this in your thread, but I think you might know the answer. If I have a UIViewController class that is the main view of the application and it contains two views (one of type UIViewController, and another of type UITableViewController, which both are wrapped in their own classes), and if I switch to one of the views when a button clicked by doing something like this:
if(self.View1 == nil) {
View1ViewController *main = [[View1ViewController alloc] initWithNibName:@"View1" bundle:[NSBundle mainBundle]];
self.View1 = main;
[main release];
UIView *theWindow = [self.view superview];
[self.view removeFromSuperview];
[theWindow addSubview:self.View1.view];
How can I return to this main view once I'm displaying View1 or View2?