From every benchmark I've seen so far, Linux has always been faster than the BSDs.

For example, look at these benchmarks from 2003[1]. The newest benchmarks I could find[2], [3] point in the same direction.

[1] http://bulk.fefe.de/scalability/

[2] https://matteocroce.it/blog/freebsd_linux_networking/

[3] https://www.phoronix.com/review/freebsd-15-amd-epyc-linux