If your API call is classified as Synchronous then:
- It means that your application will respond only when there is a response back from the API call that was previously made. Until an, unless there is a response back from API call the system or the application will not function further.
- The use of this API call is beneficial if you need any user-specific decisions that are pending. This will help the users to take appropriate decisions and based on the need the system will execute further and serve
- It is also considered as a performance lag because always it has to wait for the response from the API call and based on the response the application will react. This is the reason why they call this method as performance lag.