[mithro]

I have a Google Doc at <https://j.mp/softcpus-on-fpgas> which includes a bunch of information about what type of performance has been achieved on modern Xilinx FPGAs.

You can generally do quite a bit of parallelism, see the quad-core LiteX+VexRISCV solution at <https://antmicro.com/blog/2020/05/multicore-vex-in-litex/>.