I’m not saying that this is a perfect solution and the issues are being adressed already since there are a lot of reports for this behaviour, but it’s an adequate workaround for the time being, if it helps in your situation.
Being a heavy mobile user myself, I can confirm that this has always helped me when the app starts getting slower and it fixes the problem for about 3-4 weeks for me (but that highly depends on your usage profile).
If the fix does not work for you or your users, it must be something else and should be diagnosed in more detail then.