tdf#117066 Saving ODT document with ~1500 bookmarks is slow, part 3

Individually, these don't make much difference, but they add up
to a halving the time to save on my machine.

ManifestImport::characters was spending time adding data to an OUString,
so convert that to an OUStringBuffer.

Change-Id: I267e701f4e7998044763f44199b1fe8a37325b68
Reviewed-on: https://gerrit.libreoffice.org/70311
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

package/source/manifest/ManifestImport.cxx

@@ -173,7 +173,7 @@ void ManifestImport::doEncryptedCipherValue()
     {
         aKeyInfoSequence[2].Name = "CipherValue";
         uno::Sequence < sal_Int8 > aDecodeBuffer;
-        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters);
+        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters.toString());
         aKeyInfoSequence[2].Value <<= aDecodeBuffer;
         aCurrentCharacters = ""; // consumed
     }
@@ -187,7 +187,7 @@ void ManifestImport::doEncryptedKeyId()
     {
         aKeyInfoSequence[0].Name = "KeyId";
         uno::Sequence < sal_Int8 > aDecodeBuffer;
-        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters);
+        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters.toString());
         aKeyInfoSequence[0].Value <<= aDecodeBuffer;
         aCurrentCharacters = ""; // consumed
     }
@@ -201,7 +201,7 @@ void ManifestImport::doEncryptedKeyPacket()
     {
         aKeyInfoSequence[1].Name = "KeyPacket";
         uno::Sequence < sal_Int8 > aDecodeBuffer;
-        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters);
+        ::comphelper::Base64::decode(aDecodeBuffer, aCurrentCharacters.toString());
         aKeyInfoSequence[1].Value <<= aDecodeBuffer;
         aCurrentCharacters = ""; // consumed
     }
@@ -510,7 +510,7 @@ void SAL_CALL ManifestImport::endElement( const OUString& aName )
 
 void SAL_CALL ManifestImport::characters( const OUString& aChars )
 {
-    aCurrentCharacters += aChars;
+    aCurrentCharacters.append(aChars);
 }
 
 void SAL_CALL ManifestImport::ignorableWhitespace( const OUString& /*aWhitespaces*/ )

package/source/manifest/ManifestImport.hxx

@@ -24,6 +24,7 @@
 #include <com/sun/star/xml/sax/XDocumentHandler.hpp>
 #include <com/sun/star/beans/NamedValue.hpp>
 #include <vector>
+#include <rtl/ustrbuf.hxx>
 
 #include <HashMaps.hxx>
 
@@ -54,7 +55,7 @@ class ManifestImport final : public cppu::WeakImplHelper < css::xml::sax::XDocum
     std::vector< css::beans::NamedValue > aKeyInfoSequence;
     std::vector< css::uno::Sequence< css::beans::NamedValue > > aKeys;
     std::vector< css::beans::PropertyValue > aSequence;
-    OUString aCurrentCharacters;
+    OUStringBuffer aCurrentCharacters;
     ManifestStack aStack;
     bool bIgnoreEncryptData;
     bool bPgpEncryption;