You sure want to know that the actual Slic3r often has a big bug and produces e.g. free-standing perimeters or far too little flow at infill. There is a fix for that:
If you let the numbers In the ‘advanced’-tab at zero for their default-settings, you may be in trouble. Set them to your actual wanted extrusion-width and you are good to go!
I had the same issue years ago with slic3r. Same fix, put in the desired width and it works fine.
@Stephanie_A interesting! In the german section of http://reprap.org there are several users, including me, that recognize this behaviour only since using Slic3r 1.2.9.
Thanks @Rene_Jurack , this interesting. I never touched this part of Slic3r. Don’t like fiddling with too many setting when the prints are looking good.
I can confirm that. For me it caused some over extrusion.