How to perform mobile actions on an app within a separate thread

Are you concerned that Mobile.waitForElementPreset runs very slow?

Yes, there are many post about the slowness of Mobile keywords. For example,

The speed of keyword largely depends on how the locator expression in TestObject is written. In many cases you can find some alternative expressions that run much faster. How to write faster locators? — That is a question to be studied case-by-case. There is no silver bullet.

Sorry, I am not experienced with Mobile testing. If you want to find out a way to make your Mobile tests run faster, you should ask Mobile testing experts (@Chris_Trevarthen and others) for advices.