Ios UICollectionView重载ItemSatinDexpath速度会因大量UICollectionViewCell而减慢

我有一个

UICollectionView

，最多可以加载1000个

UICollectionView单元格。根据集合视图中单元格的数量，调用
reloadItemsAndExpaths:
时，更新UI可能需要很长时间。我已经指出问题（无论如何在我的代码中）存在于
重新加载itemsatindexpaths:
和
collectionView:cellForItemAtIndexPath:
使用以下代码：

- (void)updateIndexPath:(NSIndexPath *)indexPath 
{
    NSLog(@"starting reload of row %ld", (long)indexPath.row);
    [self.collectionView reloadItemsAtIndexPaths:@[indexPath]];
    NSLog(@"finished reload of row %ld", (long)indexPath.row);
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                  cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"begin creating cell at row %ld", (long)indexPath.row);
    // Customise the cell
    NSLog(@"end creating cell at row %ld", (long)indexPath.row);
    return cell;
}

（注意，我一次只想更新1个indexPath）

当集合视图有5个单元格时，只需40毫秒：

2014-03-14 13:07:10.949 Fotobox[2903:60b] starting reload of row 0
2014-03-14 13:07:10.954 Fotobox[2903:60b] begin creating cell at row 0
2014-03-14 13:07:10.974 Fotobox[2903:60b] end creating cell at row 0
2014-03-14 13:07:10.989 Fotobox[2903:60b] finished reload of row 0

但使用316电池需要3.4秒：

2014-03-14 13:08:48.222 Fotobox[2903:60b] starting reload of row 0
2014-03-14 13:08:51.679 Fotobox[2903:60b] begin creating cell at row 0
2014-03-14 13:08:51.708 Fotobox[2903:60b] end creating cell at row 0
2014-03-14 13:08:51.725 Fotobox[2903:60b] finished reload of row 0

我能做些什么来加快速度吗？

我猜这是UICollectionView内部的，但我希望被证明是错误的

谢谢