Fedora 26 vs. 27 Beta Benchmarks, Wayland vs. X.Org Gaming Tests
With both Fedora 26 and 27 using GCC 7 as the compiler, there aren't any major changes in the CPU workload tests.
Attributed possibly to the I/O improvements in Fedora 27, the Redis performance is stronger on F27. There's also been glibc optimizations and other work found in Fedora 27.
More details on these benchmark results can be found via this OpenBenchmarking.org result file.