Turn off the hot water at the valve under the sink. Disconnect the line from the valve to the faucet. If the line is a pipe slide a 1/2" hose over it and direct the flow into a bucket on the floor. If it is a flexable pipe just point it into a bucket. Open the valve and see if the flow slows down as it gets hot. If it doesn't slow donw then the problem is the faucet packing and the washer. These will somethimes swell up when they get hot and restrict the flow.

If, with the faucet disconnected, the flow slows down then it could be the packing in the shut off valve. You can turn off the house water at the meter, pull the top off the valve under the sink and see if the packing and washer are good. If they are old it is best to repalce the entire valve. If you decide on this be careful because if the valve is old the connecting pipe from the wall is also old. If you twist off the wall nipple the chances are good that you will have to go into the wall to the elbow.

I don't think the problem is sediment. If it were then you would have restricted flow as soon as you turned on the water.