UICollectionView scrolling is slow

I have just created a UICollectionView in which The user can add images from their phone to the photo album feature in the app. I have the images save to the a subdirectory in the documents directory so more can be added and removed. However, when I scroll up and down the collection view, it is very laggy.

How can I make the scroll nice and smooth?

My Code: The first 16 images are preset images everything after that are from a subdirectory in documents Directory

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Custom" forIndexPath:indexPath];
    //Current index number
    int index=indexPath.section * noOfSection + indexPath.row;
    //Check if its the preset photos
    if(index<16){
        NSString *name=[recipePhotos objectAtIndex:indexPath.section * noOfSection + indexPath.row];
        cell.imageView.image=[UIImage imageNamed:name];
    }

//not preset photos, so retrieve the photos the user added
    else {
        NSData *data= [NSData dataWithContentsOfFile:[recipePhotos objectAtIndex:index]];
        UIImage *theImage=[UIImage imageWithData:data];

        cell.imageView.image=theImage;
        data=nil;
    }

    return cell;
}

Time Profiler gave me this

Running Time    Self        Symbol Name
568.0ms   63.1% 0.0     Main Thread  0x4048
320.0ms   35.5% 0.0     _pthread_start  0x405e
320.0ms   35.5% 0.0      thread_start
320.0ms   35.5% 0.0       _pthread_start
320.0ms   35.5% 0.0        0x1084be960
310.0ms   34.4% 1.0         0x1084be6f0
7.0ms    0.7%   0.0         mach_msg
2.0ms    0.2%   2.0         objc_msgSend
1.0ms    0.1%   1.0         -[NSAutoreleasePool release]
4.0ms    0.4%   0.0     _dispatch_mgr_thread  0x4052
4.0ms    0.4%   0.0      _dispatch_mgr_thread
4.0ms    0.4%   0.0       _