I'm from India and i need to switch my calls from time to time, where as there's no options to change i have to go all the way to the settings> sim settings to change default calling sim I'm using ONEPLUS 9R, the default phone and message app is from Google and in both the app there's lag if they're not open in the Background. A friend of mine has the same phone and he too is facing same problem with his Handset.