Welcome to the SeeMeCNC Community

KISSlicer 1.6.2 was just release on all platforms. See the change log for details, minor fixes but one new big thing is an Object Packing Quality option on the Misc panel. Leave it at Fast but if you need better packing change it. However, note that it will take a bit of time depending on how many objects it's packing.

http://www.kisslicer.com/download.html