I'm typing this from a 2011 iMac (3.4ghz, 4-core i7, 8GB RAM, AMD 6700 series GPU) on which I've just installed Mac OS Ventura using OpenCore. It's working great. Performance is not distinguishable from the performance of the same system on High Sierra, so far. The process was also pretty easy, it walked me through every step. Just highlights how absurd it is that these systems aren't still supported.