Why does my kitchen sink have bad water pressure?

It could be that those pipes are clogged. Have you tried any type of drain cleaner to clear them? Give it a shot.

Take the screen out of the strainer it might be filled with debris

Well your dishwasher is often tee’d off the supply line of the kitchen faucet, you can usually see the connection under the sink in the cabinets. Make sure the supply valves under the sink are open all the way, be careful when turning the valves, they like to break if you apply too much force. If the valves to your kitchen faucet are open, the next question is what kind of pipe do you have in your home, copper, galvanized, PEX, CPVC. How old is your home. Homes with older pipes often times suffer from poor water pressure because the pipes scale themselves shut, especially galvanized. If this is the case in your home, time to call a plumber. I would also clean the faucet aria tor screen while your messing around with the faucet just to cover all your bases. One comment mentioned to use “drain cleaner” that won’t help your draining alright you have supply line issues. The other thing I would like to know is it both hot and cold water on that faucet that are running slow with low pressure, or is one or the other. I need to know that before I can suggest something else.

Replace the aerator in your faucet. It just screws out. A new one is only a couple $$. Good luck!