Prior to patch 1.21, Overwatch maintained two estimates for your network quality: RTT and ping. Your RTT (round trip time) was measured as the time between sending a packet to the server and hearing a response, which included some application processing time on both ends. Calculating your ping, on the other hand, required us to timestamp every packet at the exact moment it was sent or received, something that became much more expensive after we patched for Meltdown & Spectre. Without these timestamps, your ping and your RTT are effectively the same value.
Rather than report a less accurate and less stable ping, we opted to merge the ping and RTT stats into the single Latency figure you now see in Advanced Performance Stats. You can expect this Latency number to be 10-20ms more than the ping value we previously displayed (higher if your system isn’t hitting 60FPS consistently). The difference between your old Ping and the new Latency figure is purely due to the missing timestamps, and has no effect on your gameplay. Latency measurement will also be more responsive to changes in network quality – your ping previously was averaged over 15 seconds, which made it hard to notice brief latency spikes. The new value is sampled over the last 3 seconds, and should do a better job of capturing brief hiccups in connectivity.
As a part of this patch, we also disabled displaying the Latency statistic if you’re not in a match. The numbers displayed while out of a match were the last stale values from your previous match and did not reflect your current networking environment.
(We missed including this in our patch notes, sorry for any confusion!)