If your Google spreadsheet simply holds your data and you can do all of the calculations you need to do without difficult via AppSheet, then you can skip this tip. If, one the other hand, you use your app to collect fairly large amounts of data, then use extra Google sheets to do some back-end number crunching, keep reading.
This gif of Google sheets recalculating is taken from the following page by Ben Collins:
I recently had a problem of this type and my solution what to do the following:
Though it may seem counterintuitive, there are situations where using an action to write to a sheet can be faster than relying on a volatile function in the sheet. (The idea removing volatile functions like now() is one of many good ideas on Ben Collins’ page.)
Also, if you are interested in turbo charging your app to run as fast as possible, please check out that comments on the above thread. I found them to be very helpful.