Debian 7 Through Debian Testing Benchmarks With/Without Mitigations
The TTSIOD 3D Renderer performance saw a big boost out of Debian 8 but since then has been largely flat.
The x264 video encode performance has only shifted around by a few frames.
The 7-Zip performance meanwhile has been slowly improving with the newer Debian releases.
Newer Debian releases tend to compile code slower due to newer GNU Compiler Collection (GCC) releases introducing additional optimization passes that take time to execute but with striving for faster generated binaries.
The Tungsten renderer saw better performance since Debian 9.