Turning off some of the features of the onX Hunt App will reduce the amount of memory it's using which may fix the problem.
Turn off unneeded Map Layers
Map Layers contain a lot of information, so turn off any Layers you aren't currently using. Follow this link to learn how to turn on and turn off Map Layers.
Turn off Markups (Waypoints, Lines, Shapes and Tracks
If you have a large number of Markups, having them all turned on at the same time can slow your device down. Follow this link to learn how to turn on and turn Markups.
You can also save your Markups to your personal computer and delete them from your onX Hunt App to save space.
Follow this link to learn how to save Markups to your computer.
Follow this link to learn how to upload Markups back into your onX Hunt Account when you need them.
Turn off Wind & Weather
The Wind & Weather feature is in constant communication with weather stations which takes up a lot of processing power on your device. Follow this link to learn how to use the Wind & Weather feature.