Have Learner objects specify whether they want to collect node latency statistics or not. Ursulas don't currently have a use for the statistics (default is False), but Bob and Porter do for decryption requests.

nucypher/characters/lawful.py

@@ -387,6 +387,8 @@ class Alice(Character, actors.PolicyAuthor):
 
 
 class Bob(Character):
+    _TRACK_NODE_LATENCY_STATS = True
+
     banner = BOB_BANNER
     _default_dkg_variant = FerveoVariant.Simple
     _default_crypto_powerups = [SigningPower, DecryptingPower]

nucypher/network/decryption.py

@@ -79,17 +79,20 @@ class ThresholdDecryptionClient(ThresholdAccessControlClient):
             self.log.warn(message)
             raise self.ThresholdDecryptionRequestFailed(message)
 
-        ursulas_sorted_by_latency = (
+        ursulas_to_contact = (
             self._learner.node_latency_collector.order_addresses_by_latency(
                 list(encrypted_requests)
             )
+            if self._learner.node_latency_collector
+            else list(encrypted_requests)
         )
+
         # Discussion about WorkerPool parameters:
         # "https://github.com/nucypher/nucypher/pull/3393#discussion_r1456307991"
         worker_pool = WorkerPool(
             worker=worker,
             value_factory=self.ThresholdDecryptionRequestFactory(
-                ursulas_to_contact=ursulas_sorted_by_latency,
+                ursulas_to_contact=ursulas_to_contact,
                 batch_size=math.ceil(threshold * 1.25),
                 threshold=threshold,
             ),

nucypher/network/nodes.py

@@ -1,3 +1,4 @@
+import contextlib
 import time
 from collections import deque
 from contextlib import suppress
@@ -219,6 +220,8 @@ class Learner:
     _ROUNDS_WITHOUT_NODES_AFTER_WHICH_TO_SLOW_DOWN = 10
     __DEFAULT_MIDDLEWARE_CLASS = RestMiddleware
 
+    _TRACK_NODE_LATENCY_STATS = False
+
     _crashed = (
         False  # moved from Character - why was this in Character and not Learner before
     )
@@ -262,7 +265,9 @@ class Learner:
         self.log = Logger("learning-loop")  # type: Logger
         self.domain = domain
 
-        self.node_latency_collector = NodeLatencyStatsCollector()
+        self.node_latency_collector = (
+            NodeLatencyStatsCollector() if self._TRACK_NODE_LATENCY_STATS else None
+        )
 
         self.learning_deferred = Deferred()
         default_middleware = self.__DEFAULT_MIDDLEWARE_CLASS(
@@ -830,9 +835,14 @@ class Learner:
             return RELAX
 
         try:
-            with self.node_latency_collector.get_latency_tracker(
-                current_teacher.checksum_address
-            ):
+            optional_latency_context_manager = (
+                self.node_latency_collector.get_latency_tracker(
+                    current_teacher.checksum_address
+                )
+                if self.node_latency_collector
+                else contextlib.nullcontext()
+            )
+            with optional_latency_context_manager:
                 response = self.network_middleware.get_nodes_via_rest(
                     node=current_teacher,
                     announce_nodes=announce_nodes,