From the documentation
_When localThresholdMS is used :
During monitoring, drivers regularly record the RTT of ismaster commands. The Server Selection specification calls for these to be calculated using an exponentially-weighted moving average function.
If the prior average is denoted RTTt-1, then the new average (RTTt) is computed from a new RTT measurement (Xt) and a weighting factor (α) using the following formula:
The weighting factor is set to 0.2, which was chosen to put about 85% of the weight of the average RTT on the 9 most recent observations. Weighting recent observations more means that the average responds quickly to sudden changes in latency._
Would it be possible to have another similar configuration option to tell the client to observe query/operation response times over a window of time or over n executions, be able to specify a threshold for response times so that servers with best response times can be picked over slow responding servers?