I have very low hot water pressure in the kitchen only. I have disconnected the line and have great pressure from the valve. It is a two handled faucet and the cold water pressure is very good. There are no kinks in the line from the valve to the faucet. No doubt there is some build up but where to look. The aerator is clean also.
It sounds like the valve in your hot water handle has some blockage. There are hundreds of different different designs, so it's hard to diagnose without brand/model. However, many faucets are made with valve cartridges (see link below) whose narrow channels can easily pick up bits of pipe scale. Take the handle apart and have a look.