When did this lag start and is it still ongoing when you queue through the dungeon finder?
You may want to try power-cycling in case it is something related to the console causing this issue.
To power cycle your PlayStation 4:
- Press and hold the [PS] button on your controller.
- Turn off the PS4 with Turn Off PS4 and not "Enter Rest Mode".
- Make sure the light goes out on the console and then unplug its power cable and wait for 10 seconds.
- Plug the power cable back in and turn the console back on by pressing the [PS] button on your controller.