How does the app effect the performance of the spreadsheet?

Hey AppSheet Team, would love your take on this: I created a simple app for an organization doing a fundraising campaign. They have about 40-50 people using a large Google spreadsheet simultaneously and making phone calls to names on the sheet. At the same time, they had 3-4 people using the connected app to make changes to the “backend”. They found that the spreadsheet was acting very sluggish and therefore frustrating to use. Eventually they decided to stop using the app. According to them, the spreadsheet sped up and became useable again for the callers. Can you think of any reason why this might be? Does it make sense that the app would slow down the sheet, more than just another user of the spreadsheet would?

Thank you.