I personally love the new lock screen app coded by Rudy Huyn but for others the app has been too slow to make it worthwhile.
To add insult to injury , for some users the lagging remains even after uninstalling, with people being faced with many seconds of a Resuming… screen after unlocking their phone.
The solution is fortunately simple. Simply go to Settings > Lock Screen and change background to another item like Bing and then change it back to Photo. The hesitation should disappear.