diff --git a/src/client/messenger.cpp b/src/client/messenger.cpp
index d9ccc76f..2182a519 100644
--- a/src/client/messenger.cpp
+++ b/src/client/messenger.cpp
@@ -182,12 +182,13 @@ void osd_messenger_t::init()
     }
     keepalive_timer_id = tfd->set_timer(1000, true, [this](int)
     {
+        std::vector<uint64_t> clients_to_stop;
+        std::vector<osd_op_t*> ops_to_send;
         auto cl_it = clients.begin();
         while (cl_it != clients.end())
         {
             auto cl = cl_it->second;
             cl_it++;
-            auto client_id = cl->client_id;
             if (!cl->osd_num && !cl->in_osd_num || cl->peer_state != PEER_CONNECTED && cl->peer_state != PEER_RDMA)
             {
                 // Do not run keepalive on regular clients
@@ -201,9 +202,7 @@ void osd_messenger_t::init()
                     // Ping timed out, stop the client
                     fprintf(stderr, "Ping timed out for OSD %ju (client %ju), disconnecting peer\n",
                         cl->in_osd_num ? cl->in_osd_num : cl->osd_num, cl->client_id);
-                    stop_client(cl->client_id);
-                    // Restart iterator because it may be invalidated
-                    cl_it = clients.upper_bound(client_id);
+                    clients_to_stop.push_back(cl->client_id);
                 }
             }
             else if (cl->idle_time_remaining > 0)
@@ -242,9 +241,7 @@ void osd_messenger_t::init()
                     };
                     cl->ping_time_remaining = osd_ping_timeout;
                     cl->idle_time_remaining = osd_idle_timeout;
-                    outbox_push(op);
-                    // Restart iterator because it may be invalidated
-                    cl_it = clients.upper_bound(client_id);
+                    ops_to_send.push_back(op);
                 }
             }
             else
@@ -252,6 +249,14 @@ void osd_messenger_t::init()
                 cl->idle_time_remaining = osd_idle_timeout;
             }
         }
+        for (uint64_t client_id: clients_to_stop)
+        {
+            stop_client(client_id);
+        }
+        for (osd_op_t *op: ops_to_send)
+        {
+            outbox_push(op);
+        }
     });
 }
 
diff --git a/src/client/messenger.h b/src/client/messenger.h
index 83e07ce6..88b34894 100644
--- a/src/client/messenger.h
+++ b/src/client/messenger.h
@@ -12,6 +12,7 @@
 #include <deque>
 #include <vector>
 
+#include "../util/robin_hood.h"
 #include "malloc_or_die.h"
 #include "json11/json11.hpp"
 #include "msgr_op.h"
@@ -86,7 +87,7 @@ struct osd_client_t
     std::vector<osd_op_t*> received_ops;
 
     // Outbound operations
-    std::map<uint64_t, osd_op_t*> sent_ops;
+    robin_hood::unordered_flat_map<uint64_t, osd_op_t*> sent_ops;
     uint64_t send_op_id = 0;
 
     // PGs dirtied by this client's primary-writes
@@ -202,8 +203,8 @@ protected:
     uint64_t rdma_max_sge = 0, rdma_max_send = 0, rdma_max_recv = 0;
     uint64_t rdma_max_msg = 0;
     rdma_event_channel *rdmacm_evch = NULL;
-    std::map<rdma_cm_id*, osd_client_t*> rdmacm_connections;
-    std::map<rdma_cm_id*, rdmacm_connecting_t*> rdmacm_connecting;
+    robin_hood::unordered_flat_map<rdma_cm_id*, osd_client_t*> rdmacm_connections;
+    robin_hood::unordered_flat_map<rdma_cm_id*, rdmacm_connecting_t*> rdmacm_connecting;
 #endif
 
     std::vector<msgr_iothread_t*> iothreads;
@@ -219,10 +220,10 @@ public:
     // osd_num_t is only for logging and asserts
     uint64_t next_client_id = 1;
     osd_num_t osd_num;
-    std::map<uint64_t, osd_client_t*> clients;
-    std::map<uint64_t, osd_client_t*> osd_peers;
-    std::map<int, osd_client_t*> clients_by_fd;
-    std::map<osd_num_t, osd_wanted_peer_t> wanted_peers;
+    robin_hood::unordered_flat_map<uint64_t, osd_client_t*> clients;
+    robin_hood::unordered_flat_map<uint64_t, osd_client_t*> osd_peers;
+    robin_hood::unordered_flat_map<int, osd_client_t*> clients_by_fd;
+    robin_hood::unordered_flat_map<osd_num_t, osd_wanted_peer_t> wanted_peers;
     std::vector<std::string> osd_networks;
     std::vector<addr_mask_t> osd_network_masks;
     std::vector<std::string> osd_cluster_networks;
diff --git a/src/osd/osd_primary_subops.cpp b/src/osd/osd_primary_subops.cpp
index 4f2ff8ce..e3314b44 100644
--- a/src/osd/osd_primary_subops.cpp
+++ b/src/osd/osd_primary_subops.cpp
@@ -641,7 +641,7 @@ int osd_t::submit_primary_sync_subops(osd_op_t *cur_op)
     op_data->done = op_data->errors = op_data->errcode = 0;
     op_data->n_subops = n_osds;
     op_data->subops = subops;
-    std::map<uint64_t, osd_client_t*>::iterator peer_it;
+    robin_hood::unordered_flat_map<uint64_t, osd_client_t*>::iterator peer_it;
     for (int i = 0; i < n_osds; i++)
     {
         osd_num_t sync_osd = op_data->dirty_osds[i];