Where the slot goes: six instruments, calibrated
Over three days in August, Lodestar timed 21,530 newPayload calls to its Ethrex peer and reported a mean of 372.6 ms; Ethrex timed the same calls from its own end of the same socket and reported 164.8 ms. Both figures are right as far as the client reporting them is concerned, since the two stopwatches start and stop at different points, but the 208 ms between them is larger than most of the differences this series has spent six editions measuring between execution clients.
For six editions we compared execution clients through whichever consensus client happened to be watching them, and it took until the sixth to work out how much of what we were reading belonged to the watcher rather than the watched. Six consensus clients run against the same fleet here, no two of them measure a slot the same way, and one of them cannot produce a mean for the engine call at all.