I replaced my kitchen sink which was old and chip but working fine. Drain for this sink was in the corner, new sink is in the middle.
Old sink was installed with pvc as drain no trap just a straight line from sink drain to main drain.
This worked fine. New drain not as straight because drain hole is in the middle of new sink.
No leaks but a slow drain. What to do??

Try this first. Plug one side of the sink with the stopper,, have someone hold the stopper down, then run water in the other side of the sink until it has an inch or two of water in it, then plunge that side of the sink vigorously. If this doesn't help, you will need to either use a small auger to clean the drain from under the sink, or use a medium auger to clean the drain from the sink vent on the roof.

Couple other question... how much drain pipe was replaced when they changed location of the drain? Do you have a Garbage disposal? Do both sides of the sink drain slow, or just one? When you fill one side of the sink, and then let it go, does it back up into the other side of the sink?(the last question is very important. If you can fill one side of the sink to the rim, then let it go, and it doesn't back up into the other side of the sink, this normally indicates a clear drain). Please let me know what you find.

There is only one side not two. There was no drain problem before change.
There is 12-15 inches from sink to drain in floor and that's what was changed.no garbage disposal but have dishwasher. It seem like a vacuum problem. When the sink fills up the water just seems to trickle down the drain.when water is run at half pressure sink is fine

Is the sink vented? Sounds like you will have to auger the drain. Can you take a picture of the piping under the sink? It will give us a better idea of what the problem may be.

The sink is not vented. The drain pipe was open for 1 hour while pipe were changed I know nothing went down while open pipe were clear and drain well before anything was changed. The sink was never vented why would it need it now?? Don't know how to uplink picture to show drain.