Edit: this has already been corrected in the above study & images.
A Quick Update
After a conversation with Dan Appel, I was able to pass extra arguments through to the compiler to make release optimizations with:
swift build -Xswiftc -O
This means that I was able to get results that are even closer to comparable, and faster. The resutls of the extra testing are as follows:
I will update the images and post an edit when it is ready, but tonight I need some sleep.