diff --git a/src/core/slavebase.cpp b/src/core/slavebase.cpp
--- a/src/core/slavebase.cpp
+++ b/src/core/slavebase.cpp
@@ -547,6 +547,7 @@
         if (!d->m_rootEntryListed) {
             qCWarning(KIO_CORE) << "UDSEntry for '.' not found, creating a default one. Please fix the" << QCoreApplication::applicationName() << "KIO slave";
             KIO::UDSEntry entry;
+            entry.reserve(4);
             entry.fastInsert(KIO::UDSEntry::UDS_NAME, QStringLiteral("."));
             entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFDIR);
             entry.fastInsert(KIO::UDSEntry::UDS_SIZE, 0);
diff --git a/src/ioslaves/ftp/ftp.cpp b/src/ioslaves/ftp/ftp.cpp
--- a/src/ioslaves/ftp/ftp.cpp
+++ b/src/ioslaves/ftp/ftp.cpp
@@ -1288,6 +1288,7 @@
 {
     Q_ASSERT(entry.count() == 0); // by contract :-)
 
+    entry.reserve(9);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, filename);
     entry.fastInsert(KIO::UDSEntry::UDS_SIZE, ftpEnt.size);
     entry.fastInsert(KIO::UDSEntry::UDS_MODIFICATION_TIME, ftpEnt.date.toSecsSinceEpoch());
@@ -1322,6 +1323,7 @@
 {
     UDSEntry entry;
 
+    entry.reserve(4);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, filename);
     entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, isDir ? S_IFDIR : S_IFREG);
     entry.fastInsert(KIO::UDSEntry::UDS_ACCESS, S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
@@ -1369,6 +1371,7 @@
     // We can't stat root, but we know it's a dir.
     if (path.isEmpty() || path == QLatin1String("/")) {
         UDSEntry entry;
+        entry.reserve(6);
         //entry.insert( KIO::UDSEntry::UDS_NAME, UDSField( QString() ) );
         entry.fastInsert(KIO::UDSEntry::UDS_NAME, QStringLiteral("."));
         entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFDIR);
diff --git a/src/ioslaves/http/http.cpp b/src/ioslaves/http/http.cpp
--- a/src/ioslaves/http/http.cpp
+++ b/src/ioslaves/http/http.cpp
@@ -719,6 +719,7 @@
 
         // When downloading we assume it exists
         UDSEntry entry;
+        entry.reserve(3);
         entry.fastInsert(KIO::UDSEntry::UDS_NAME, url.fileName());
         entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFREG);   // a file
         entry.fastInsert(KIO::UDSEntry::UDS_ACCESS, S_IRUSR | S_IRGRP | S_IROTH);   // readable by everybody
diff --git a/src/ioslaves/remote/remoteimpl.cpp b/src/ioslaves/remote/remoteimpl.cpp
--- a/src/ioslaves/remote/remoteimpl.cpp
+++ b/src/ioslaves/remote/remoteimpl.cpp
@@ -122,6 +122,7 @@
 void RemoteImpl::createTopLevelEntry(KIO::UDSEntry &entry) const
 {
     entry.clear();
+    entry.reserve(8);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, QStringLiteral("."));
     entry.fastInsert(KIO::UDSEntry::UDS_DISPLAY_NAME, i18n("Network"));
     entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFDIR);
@@ -155,6 +156,7 @@
         return false;
     }
 
+    entry.reserve(7);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, i18n("Add Network Folder"));
     entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFREG);
     entry.fastInsert(KIO::UDSEntry::UDS_URL, Strings::wizardUrl());
@@ -193,6 +195,7 @@
     QString new_filename = file;
     new_filename.chop(8);
 
+    entry.reserve(8);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, desktop.readName());
     entry.fastInsert(KIO::UDSEntry::UDS_URL, QLatin1String("remote:/") + new_filename);
 
diff --git a/src/ioslaves/trash/kio_trash.cpp b/src/ioslaves/trash/kio_trash.cpp
--- a/src/ioslaves/trash/kio_trash.cpp
+++ b/src/ioslaves/trash/kio_trash.cpp
@@ -285,6 +285,7 @@
 void TrashProtocol::createTopLevelDirEntry(KIO::UDSEntry &entry)
 {
     entry.clear();
+    entry.reserve(8);
     entry.fastInsert(KIO::UDSEntry::UDS_NAME, QStringLiteral("."));
     entry.fastInsert(KIO::UDSEntry::UDS_DISPLAY_NAME, i18n("Trash"));
     entry.fastInsert(KIO::UDSEntry::UDS_FILE_TYPE, S_IFDIR);
@@ -438,6 +439,7 @@
 
 bool TrashProtocol::createUDSEntry(const QString &physicalPath, const QString &displayFileName, const QString &internalFileName, KIO::UDSEntry &entry, const TrashedFileInfo &info)
 {
+    entry.reserve(13);
     QByteArray physicalPath_c = QFile::encodeName(physicalPath);
     QT_STATBUF buff;
     if (QT_LSTAT(physicalPath_c.constData(), &buff) == -1) {
diff --git a/src/widgets/renamedialog.cpp b/src/widgets/renamedialog.cpp
--- a/src/widgets/renamedialog.cpp
+++ b/src/widgets/renamedialog.cpp
@@ -219,6 +219,7 @@
         } else {
             UDSEntry srcUds;
 
+            srcUds.reserve(4);
             srcUds.fastInsert(UDSEntry::UDS_NAME, d->src.fileName());
             srcUds.fastInsert(UDSEntry::UDS_MODIFICATION_TIME, mtimeSrc.toMSecsSinceEpoch() / 1000);
             srcUds.fastInsert(UDSEntry::UDS_CREATION_TIME, ctimeSrc.toMSecsSinceEpoch() / 1000);
@@ -232,6 +233,7 @@
         } else {
             UDSEntry destUds;
 
+            destUds.reserve(4);
             destUds.fastInsert(UDSEntry::UDS_NAME, d->dest.fileName());
             destUds.fastInsert(UDSEntry::UDS_MODIFICATION_TIME, mtimeDest.toMSecsSinceEpoch() / 1000);
             destUds.fastInsert(UDSEntry::UDS_CREATION_TIME, ctimeDest.toMSecsSinceEpoch() / 1000);