Run it at Full Power for acrylic, but adjust the speed.
The warping is because of too much concentrated heat with those narrow cuts. You can do like the others have suggested and set up the file in your design software so there are 3 or 4 different colors so the GFUI will create 3 or 4 operations. This will allow you to make the laser head cut one rectangle then move over to another area of the material for the next one, while giving the previous cut area some time to cool down.
You can also increase the speed of the head so there is less power going into the material, thus less heat, less char, less risk of warping, but then you need to specify multiple passes in order to cut completely through the material.