I made a copter using pixhawk 2.4.8.
The response to the throttle movement is too slow.
Is there a way to speed up the throttle response?
The throttle response really depends on the battery, connections, ESC/motor/prop selection, along with the takeoff weight.
You would need to provide more hardware details plus a .bin log and an outline of what configuration you have done.
The Pixhawk 2.4.8 itself doesnt dictate whether throttle response is fast or slow.
You need to upload the .bin log to a filesharing service such as onedrive, dropbox or similar, then provide the link to your file.
Also provide the hardware details.
If you are building a large agri drone and planning on doing real work with it, a Pixhawk 2.4.8 may not be reliable as it is a cheap copy of an original Pixhawk, Quality parts selection will be key to keeping this copter flying.