diff --git a/sessionsandsubscriptionsdb.cpp b/sessionsandsubscriptionsdb.cpp
index b9b2bf5..2a85721 100644
--- a/sessionsandsubscriptionsdb.cpp
+++ b/sessionsandsubscriptionsdb.cpp
@@ -183,7 +183,7 @@ void SessionsAndSubscriptionsDB::writeRowHeader()
 
 }
 
-void SessionsAndSubscriptionsDB::saveData(const std::list<std::unique_ptr<Session>> &sessions, const std::unordered_map<std::string, std::list<SubscriptionForSerializing>> &subscriptions)
+void SessionsAndSubscriptionsDB::saveData(const std::vector<std::unique_ptr<Session>> &sessions, const std::unordered_map<std::string, std::list<SubscriptionForSerializing>> &subscriptions)
 {
     if (!f)
         return;
diff --git a/sessionsandsubscriptionsdb.h b/sessionsandsubscriptionsdb.h
index 15a242e..9b5f63a 100644
--- a/sessionsandsubscriptionsdb.h
+++ b/sessionsandsubscriptionsdb.h
@@ -64,7 +64,7 @@ public:
     void openWrite();
     void openRead();
 
-    void saveData(const std::list<std::unique_ptr<Session>> &sessions, const std::unordered_map<std::string, std::list<SubscriptionForSerializing>> &subscriptions);
+    void saveData(const std::vector<std::unique_ptr<Session>> &sessions, const std::unordered_map<std::string, std::list<SubscriptionForSerializing>> &subscriptions);
     SessionsAndSubscriptionsResult readData();
 };
 
diff --git a/subscriptionstore.cpp b/subscriptionstore.cpp
index 75f926a..cc88461 100644
--- a/subscriptionstore.cpp
+++ b/subscriptionstore.cpp
@@ -639,7 +639,8 @@ void SubscriptionStore::saveSessionsAndSubscriptions(const std::string &filePath
 
     // First copy the sessions...
 
-    std::list<std::unique_ptr<Session>> sessionCopies;
+    std::vector<std::unique_ptr<Session>> sessionCopies;
+    sessionCopies.reserve(sessionsByIdConst.size());
 
     for (const auto &pair : sessionsByIdConst)
     {