diff --git a/include/maxscale/session_stats.hh b/include/maxscale/session_stats.hh
index d5c9984d1..6c5c8566e 100644
--- a/include/maxscale/session_stats.hh
+++ b/include/maxscale/session_stats.hh
@@ -15,7 +15,7 @@
 #include <maxscale/ccdefs.hh>
 
 
-#include <map>
+#include <unordered_map>
 
 #include <maxscale/server.h>
 #include <maxbase/average.hh>
@@ -59,5 +59,5 @@ private:
     maxbase::CumulativeAverage m_num_ave_session_selects;
 };
 
-using SrvStatMap = std::map<SERVER*, ServerStats>;
+using SrvStatMap = std::unordered_map<SERVER*, ServerStats>;
 }
diff --git a/server/modules/routing/readwritesplit/readwritesplit.cc b/server/modules/routing/readwritesplit/readwritesplit.cc
index 01d9dff9b..b71c062c7 100644
--- a/server/modules/routing/readwritesplit/readwritesplit.cc
+++ b/server/modules/routing/readwritesplit/readwritesplit.cc
@@ -107,9 +107,9 @@ const Stats& RWSplit::stats() const
     return m_stats;
 }
 
-ServerStats& RWSplit::server_stats(SERVER* server)
+SrvStatMap& RWSplit::local_server_stats()
 {
-    return (*m_server_stats)[server];
+    return *m_server_stats;
 }
 
 maxscale::SrvStatMap RWSplit::all_server_stats() const
diff --git a/server/modules/routing/readwritesplit/readwritesplit.hh b/server/modules/routing/readwritesplit/readwritesplit.hh
index 02823f6ef..f4364311f 100644
--- a/server/modules/routing/readwritesplit/readwritesplit.hh
+++ b/server/modules/routing/readwritesplit/readwritesplit.hh
@@ -264,7 +264,7 @@ public:
     const Config& config() const;
     Stats&        stats();
     const Stats&  stats() const;
-    ServerStats&  server_stats(SERVER* server);
+    SrvStatMap&   local_server_stats();
     SrvStatMap    all_server_stats() const;
 
     int  max_slave_count() const;
diff --git a/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc b/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
index ba363319d..65cf6092f 100644
--- a/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
+++ b/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
@@ -477,8 +477,8 @@ bool RWSplitSession::route_session_write(GWBUF* querybuf, uint8_t command, uint3
             {
                 nsucc += 1;
                 mxb::atomic::add(&backend->server()->stats.packets, 1, mxb::atomic::RELAXED);
-                m_router->server_stats(backend->server()).total++;
-                m_router->server_stats(backend->server()).read++;
+                m_server_stats[backend->server()].total++;
+                m_server_stats[backend->server()].read++;
 
                 if (expecting_response)
                 {
@@ -853,7 +853,7 @@ SRWBackend RWSplitSession::handle_slave_is_target(uint8_t cmd, uint32_t stmt_id)
     if (target)
     {
         mxb::atomic::add(&m_router->stats().n_slave, 1, mxb::atomic::RELAXED);
-        m_router->server_stats(target->server()).read++;
+        m_server_stats[target->server()].read++;
         mxb_assert(target->in_use() || target->can_connect());
     }
     else
@@ -990,7 +990,7 @@ bool RWSplitSession::handle_master_is_target(SRWBackend* dest)
     if (target && target == m_current_master)
     {
         mxb::atomic::add(&m_router->stats().n_master, 1, mxb::atomic::RELAXED);
-        m_router->server_stats(target->server()).write++;
+        m_server_stats[target->server()].write++;
     }
     else
     {
@@ -1170,7 +1170,7 @@ bool RWSplitSession::handle_got_target(GWBUF* querybuf, SRWBackend& target, bool
 
         mxb::atomic::add(&m_router->stats().n_queries, 1, mxb::atomic::RELAXED);
         mxb::atomic::add(&target->server()->stats.packets, 1, mxb::atomic::RELAXED);
-        m_router->server_stats(target->server()).total++;
+        m_server_stats[target->server()].total++;
 
         if (!m_qc.large_query() && response == mxs::Backend::EXPECT_RESPONSE)
         {
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index aa0d31e6f..705dc1047 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -45,6 +45,7 @@ RWSplitSession::RWSplitSession(RWSplit* instance,
     , m_retry_duration(0)
     , m_is_replay_active(false)
     , m_can_replay_trx(true)
+    , m_server_stats(instance->local_server_stats())
 {
     if (m_config.rw_max_slave_conn_percent)
     {
@@ -84,7 +85,7 @@ RWSplitSession* RWSplitSession::create(RWSplit* router, MXS_SESSION* session)
 
             for (auto& b : backends)
             {
-                router->server_stats(b->server()).start_session();
+                rses->m_server_stats[b->server()].start_session();
             }
         }
     }
@@ -122,9 +123,9 @@ void RWSplitSession::close()
         }
         backend->response_stat().reset();
 
-        m_router->server_stats(backend->server()).end_session(backend->session_timer().split(),
-                                                              backend->select_timer().total(),
-                                                              backend->num_selects());
+        m_server_stats[backend->server()].end_session(backend->session_timer().split(),
+                                                      backend->select_timer().total(),
+                                                      backend->num_selects());
     }
 }
 
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.hh b/server/modules/routing/readwritesplit/rwsplitsession.hh
index 426af5f61..ed769b058 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.hh
+++ b/server/modules/routing/readwritesplit/rwsplitsession.hh
@@ -169,6 +169,10 @@ public:
 
     otrx_state m_otrx_state = OTRX_INACTIVE;    /**< Optimistic trx state*/
 
+    SrvStatMap& m_server_stats;     /**< The server stats local to this thread, cached in the session object.
+                                     * This avoids the lookup involved in getting the worker-local value from
+                                     * the worker's container.*/
+
 private:
     RWSplitSession(RWSplit* instance,
                    MXS_SESSION* session,