Does it eventually get fully hot? If not, and you have a single-lever faucet, suspect that the valve may be bad. Has someone added a recirculation valve/pump that might be bad?
To troubleshoot that, you could disconnect the hot supply at the shutoff under the kitchen sink, remove the hot line feeding the faucet and run a temporary line into a bucket. Turn the shutoff back on and if that gets hot as quickly as you'd expect, you've confirmed the problem is in the kitchen faucet.
For other ideas, we'll need to know (or you'll need to think about) how your house is laid out. Is the kitchen far from the water heater? Is there a mixing valve plumbed into the line supplying the kitchen? Does the hot line run through uninsulated space? Is the hot line excessively large or long (40' of 3/4" copper pipe holds a gallon of water; 1/2" copper holds about half that.)?