This change is not able to be toggled in the current release of Simplify3D. This helps when you are printing multiple materials which won't adhere very well to each other. This change came along with other optimizations for dual-material printing. https://www.simplify3d.com/software/release-notes/
If you've not uninstalled 4.0.1, you can still utilize that version from your list of installed programs.
"A bird does not sing because it has an answer. It sings because it has a song."