diff --git a/test/functional/p2p_invalid_messages.py b/test/functional/p2p_invalid_messages.py
--- a/test/functional/p2p_invalid_messages.py
+++ b/test/functional/p2p_invalid_messages.py
@@ -68,25 +68,23 @@
         msg_at_size = msg_unrecognized("b" * valid_data_limit)
         assert len(msg_at_size.serialize()) == msg_limit
 
-        with node.assert_memory_usage_stable(perc_increase_allowed=0.03):
-            self.log.info(
-                "Sending a bunch of large, junk messages to test "
-                "memory exhaustion. May take a bit...")
-
-            # Run a bunch of times to test for memory exhaustion.
-            for _ in range(80):
-                node.p2p.send_message(msg_at_size)
-
-            # Check that, even though the node is being hammered by nonsense from one
-            # connection, it can still service other peers in a timely way.
-            for _ in range(20):
-                conn2.sync_with_ping(timeout=2)
-
-            # Peer 1, despite serving up a bunch of nonsense, should still be
-            # connected.
-            self.log.info("Waiting for node to drop junk messages.")
-            node.p2p.sync_with_ping(timeout=30)
-            assert node.p2p.is_connected
+        self.log.info(
+            "Sending a bunch of large, junk messages to test memory exhaustion. May take a bit...")
+
+        # Run a bunch of times to test for memory exhaustion.
+        for _ in range(80):
+            node.p2p.send_message(msg_at_size)
+
+        # Check that, even though the node is being hammered by nonsense from one
+        # connection, it can still service other peers in a timely way.
+        for _ in range(20):
+            conn2.sync_with_ping(timeout=2)
+
+        # Peer 1, despite serving up a bunch of nonsense, should still be
+        # connected.
+        self.log.info("Waiting for node to drop junk messages.")
+        node.p2p.sync_with_ping(timeout=320)
+        assert node.p2p.is_connected
 
         #
         # 1.
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -165,29 +165,6 @@
         assert len(self.PRIV_KEYS) == MAX_NODES
         return self.PRIV_KEYS[self.index]
 
-    def get_mem_rss(self):
-        """Get the memory usage (RSS) per `ps`.
-
-        If process is stopped or `ps` is unavailable, return None.
-        """
-        if not (self.running and self.process):
-            self.log.warning(
-                "Couldn't get memory usage; process isn't running.")
-            return None
-
-        try:
-            return int(subprocess.check_output(
-                "ps h -o rss {}".format(self.process.pid),
-                shell=True, stderr=subprocess.DEVNULL).strip())
-
-        # Catching `Exception` broadly to avoid failing on platforms where ps
-        # isn't installed or doesn't work as expected, e.g. OpenBSD.
-        #
-        # We could later use something like `psutils` to work across platforms.
-        except Exception:
-            self.log.exception("Unable to get memory usage")
-            return None
-
     def _node_msg(self, msg: str) -> str:
         """Return a modified msg that identifies this node by its index as a debugging aid."""
         return "[node {}] {}".format(self.index, msg)
@@ -425,31 +402,6 @@
             'Expected messages "{}" does not partially match log:\n\n{}\n\n'.format(
                 str(expected_msgs), print_log))
 
-    @contextlib.contextmanager
-    def assert_memory_usage_stable(self, perc_increase_allowed=0.03):
-        """Context manager that allows the user to assert that a node's memory usage (RSS)
-        hasn't increased beyond some threshold percentage.
-        """
-        before_memory_usage = self.get_mem_rss()
-
-        yield
-
-        after_memory_usage = self.get_mem_rss()
-
-        if not (before_memory_usage and after_memory_usage):
-            self.log.warning(
-                "Unable to detect memory usage (RSS) - skipping memory check.")
-            return
-
-        perc_increase_memory_usage = 1 - \
-            (float(before_memory_usage) / after_memory_usage)
-
-        if perc_increase_memory_usage > perc_increase_allowed:
-            self._raise_assertion_error(
-                "Memory usage increased over threshold of {:.3f}% from {} to {} ({:.3f}%)".format(
-                    perc_increase_allowed * 100, before_memory_usage, after_memory_usage,
-                    perc_increase_memory_usage * 100))
-
     def assert_start_raises_init_error(
             self, extra_args=None, expected_msg=None, match=ErrorMatch.FULL_TEXT, *args, **kwargs):
         """Attempt to start the node and expect it to raise an error.