Yes replace rubber hose with copper pipework and new outside tap with non return valve.also check that you are connected to mains water supply and not storage from tank in attic space.

The above comments are spot on, it should have the same flow as your kitchen tap. A plumber can fix this in no time.

Make sure that the tap contains backflow protection and an additional double check valve is fitted to comply with Water regs, this is to stop legionella bacteria back flowing and infecting into your main wholesome water supply.

Kind regards,

From what you are describing it sounds like you have a cheap DIY kit installed which are really not good. They are designed for easy connectivity without turning the water off but effectively cause pipe damage & more problems down the line.
If I am right, you will have a metal clamp around a 15mm copper water pipe indoors, with either a small knob or little T bar with which to close the water supply & the plastic hose connects to that & then off to your outside tap. Well the way these work is that it is clamped to the pipe with a rubber gasket for a seal & then a hollow steel spike is wound in to pierce the pipe, wound down to a rubber seal to prevent it leaking. The trouble is that the hollow spike is where the water flows which reduces the flow rate & over time it goes rusty & gets even narrower & blocks. I would advise doing away with this & plumbing the tap in properly which will mean cutting away the damaged pipe section. This will need fitting with a separate stop cock & drain off valve, as well as a double check valve if there is not 1 further back in the mains supply. The latter is often found as manufactured into some outside taps to comply with regulations but if the mains supply already has 1 then that wouldn't be required & a standard tap would be fine. The latter would make for easier draining in the winter. Hope this helps.

Best thing is always to check the incoming pressure of the mains coming in and see if it's the same at the outside tap. If it is then problem solved, if not check pressure from pipe attaching to hose, if pressure is good there then personally I would change it to copper as there may be a restriction somewhere or pipework crimped in wall etc. If pressure is still poor then you need to keep tracing it back to find the problem

Copper should not be run outside depending upon your electrical earthing arrangements. In PME earthing which is the most common certain common faults will result in the tap being live and outside the equipotential zone. There should always be an insulating piece of plastic to isolate from earth. Wish Plumber’s would do this as it’s a fatal fault and rcd will not help