Severe lag swiping up on lock screen

App version: F-Droid 2.1.2

Android version: 5.0.2 (rooted) Stock ROM

Device model: Moto G 2014 XT1072

Expected behaviour: To swipe upwards with no lag

Current behaviour: On 4 podcasts I listen to, when on the lock screen if I swipe upwards it doesn’t immediately remove the lock screen to show the app. Instead sometimes it does nothing at all or sometimes it does it really slowly. This is only an issue with the following:

Other ones (new user link limit reached):
james o’brien’s mystery hour
Full disclosure with james o’brien

First occurred:2 weeks ago

Steps to reproduce:
Open AntennaPod, select play on a podcast from one of the ones I’ve mentioned above. Click the power button so the phone screen goes black. Click power button again to wake up screen. Now swipe upwards to access phone.

I’m not sure what’s causing it. Could be related to podcast image?