Hi! I have updated the branch benchmarks in the pyperformance server and now they include 3.9. There are some benchmarks that are faster but on the other hand some benchmarks are substantially slower, pointing at a possible performance regression in 3.9 in some aspects. In particular some tests like "unpack sequence" are almost 20% slower. As there are some other tests were 3.9 is faster, is not fair to conclude that 3.9 is slower, but this is something we should look into in my opinion. You can check these benchmarks I am talking about by: * Go here: https://speed.python.org/comparison/ * In the left bar, select "lto-pgo latest in branch '3.9'" and "lto-pgo latest in branch '3.8'" * To better read the plot, I would recommend to select a "Normalization" to the 3.8 branch (this is in the top part of the page) and to check the "horizontal" checkbox. These benchmarks are very stable: I have executed them several times over the weekend yielding the same results and, more importantly, they are being executed on a server specially prepared to running reproducible benchmarks: CPU affinity, CPU isolation, CPU pinning for NUMA nodes, CPU frequency is fixed, CPU governor set to performance mode, IRQ affinity is disabled for the benchmarking CPU nodes...etc so you can trust these numbers. I kindly suggest for everyone interested in trying to improve the 3.9 (and master) performance, to review these benchmarks and try to identify the problems and fix them or to find what changes introduced the regressions in the first place. All benchmarks are the ones being executed by the pyperformance suite ( https://github.com/python/pyperformance) so you can execute them locally if you need to. --- On a related note, I am also working on the speed.python.org server to provide more automation and ideally some integrations with GitHub to detect performance regressions. For now, I have done the following: * Recompute benchmarks for all branches using the same version of pyperformance (except master) so they can be compared with each other. This can only be seen in the "Comparison" tab: https://speed.python.org/comparison/ * I am setting daily builds of the master branch so we can detect performance regressions with daily granularity. These daily builds will be located in the "Changes" and "Timeline" tabs ( https://speed.python.org/timeline/). * Once the daily builds are working as expected, I plan to work on trying to automatically comment or PRs or on bpo if we detect that a commit has introduced some notable performance regression. Regards from sunny London, Pablo Galindo Salgado.