MongoDB Realm: Create User is Slow

We have MongoDB Atlas with App Services & Data Services and are using this method to create a user but it consistently takes 1200ms to 1800ms

Is there any way to speed this up?
  method: 'POST',
  headers: {
    'Accept': 'application.json',
    'Content-Type': 'application/json',
    'Authorization': `Bearer &Token&`
  body: JSON.stringify({"email": "", "password": "12345678!", "status": "Pending"})

I have tried increasing the size of the Database but this made no difference