I am confused what you are asking for. In a manual sequential transmission with dog gears you do not get "from fifth to first as fast as I could press the shift down button". The engine RPM and gearbox RPM have to be very close on every shift, or you put extreme loads on the transmission. The clutch is simply a device to control the load on the transmission.
There is no such thing as instant shifts in real transmission systems. Even when computer controlled (DSG), the engine speed must be matched to the transmission speed to shift gears (aka auto-blip).