GCC 9.0 Compiler Benchmarks Against GCC7/GCC8 At The End Of 2018
The ebizzy synthetic server benchmark did see slightly better performance when built by GCC9.
Newer compiler releases do tend to mean slower compile times due to the additional optimization passes, etc, of the new compilers.
The C-Ray multi-threaded ray-tracer did see another performance improvement with GCC9 on the Core i9 system.
The Bullet physics library did see a number of minor performance improvements out of this in-development GNU compiler.