On reads, of course LMDB blows all the other away, as usual. Interestingly, they test with 4, 8, 16, and 32 concurrent reader threads on a Ryzen 5900X CPPU which only has 12 cores / 24 hardware threads.
Again, as expected, the LMDB read rate scales linearly from 1 / 4 / 8 threads, at 556ms / 141ms / 72ms. Essentially perfect scaling. The jump to 16 threads and 47ms isn't linear because the CPU has run out of cores, likewise for 32 threads at 44ms.