AFAIK that's an incorrect meme that just won't die. The performance issues you're thinking of have nothing to do with the filesystem itself, but with the I/O subsystem in Windows more generally. If you have evidence otherwise please share.
For example ReFS removed the MFT which caused various problems.
The MFT was annoying because if you create 1 mil files, and the delete them, the MFT will not be shrunk back.
Have you ever benchmarked it against NTFS? With the same exact set of FS filter drivers running on both? How much does the performance differ?