If I understand your issue correctly is that moving a slider on your Android app sends too many requests to your device.
What you need a way to throttle the requests being sent by the Android.
I don’t have a complete solution for you but I would try using the Handler class.
When the slider starts moving, send the position to the device right away, save the last position sent to an instance variable, start a timer with
postDelayed in 500 ms and mark the timer started in an instance variable.
If the slider moves while the timer is started and before it fires, save the new position to send in another instance variable.
When the timer fires check if the new position to send is the same as the last position sent. If it’s the same, mark the timer as stopped. If it’s different, send the new position, save it as the last position and start another timer with
postDelayed (i.e. follow the exact same steps as above).
This way, the servo will start moving right away but won’t be sent a new position more than once every 500ms.