I agree with what Hillhiker said on page 1, backed up by what jimbob said on page 2.
Ninthace, your mission, should you decide to accept it, is to do the same walk running only the OS app. Then do the same walk again running only the VR app.
My uneducated guess would be that if you don't have the same problem then the problem is/was the apps struggling for dominance over each other regarding resources (your phone's GPS and processor functions). If you do get the same problem then it's most likely your phone.... basically confirming what Hillhiker and jimbob have said.
Now, chill and go for a nice walkies