Cut Settings - Offset Fill Mode
This mode is a recent addition, and will fill an outline with lines that follow the shape of the object. If you have ever worked with a CNC router, it would be called an "offset pocket" operation. The image below shows a normal "raster fill" on the left and an "offset fill" on the right:
Raster fill is preferred for general use, however offset fill can save time in certain cases if you have a slower machine, or the shape you are filling is hollow, like this:
In this case, you can see that the left image has many more traversal moves (non-cutting movement of the laser, shown in red), where the right side does not. Be advised that offset fills take considerably longer to generate because of the high computation complexity.