I feel your question is a bit contradictory/too broad of a scope. You will first need to decide what exactly you want to test..

Manual testing is usually only good for functional testing (seeing if it works the way it should). If you want to do performance testing there are multiple tooling options to consider:

1. do you want to test the app itself (GUI) on a mobile device, if yes then you are looking in to something like Ranorex.
2. Do you want to do a performance/load test of the backend that the app is using then you can consider JMeter. You can record the steps from the mobile device using a local proxy (on a PC device) and play these steps back with a predefined amount of users/iterations/...

I feel your question is a bit contradictory/too broad of a scope. You will first need to decide what exactly you want to test..

Manual testing is usually only good for functional testing (seeing if it works the way it should). If you want to do performance testing there are multiple tooling options to consider:

1. do you want to test the app itself (GUI) on a mobile device, if yes then you are looking in to something like Ranorex.
2. Do you want to do a performance/load test of the backend that the app is using then you can consider JMeter. You can record the steps from the mobile device using a local proxy (on a PC device) and play these steps back with a predefined amount of users/iterations/...