diff --git a/arangod/Utils/Transaction.cpp b/arangod/Utils/Transaction.cpp
index f3121e262d..7f8c317d7c 100644
--- a/arangod/Utils/Transaction.cpp
+++ b/arangod/Utils/Transaction.cpp
@@ -938,7 +938,11 @@ void Transaction::extractKeyAndRevFromDocument(VPackSlice slice,
     } else if (*p == basics::VelocyPackHelper::RevAttribute) {
       VPackSlice revSlice(p + 1);
       if (revSlice.isString()) {
-        revisionId = basics::StringUtils::uint64(revSlice.copyString());
+        // use specialized conversion method for trusted input, that also 
+        // does not create a temporary std::string
+        VPackValueLength revLength;
+        char const* rev = revSlice.getString(revLength);
+        revisionId = basics::StringUtils::uint64_trusted(rev, revLength);
       } else if (revSlice.isNumber()) {
         revisionId = revSlice.getNumericValue<TRI_voc_rid_t>();
       }
diff --git a/arangod/VocBase/compactor.cpp b/arangod/VocBase/compactor.cpp
index ca451d9507..2f84357ea6 100644
--- a/arangod/VocBase/compactor.cpp
+++ b/arangod/VocBase/compactor.cpp
@@ -475,10 +475,14 @@ static bool CalculateSize(TRI_df_marker_t const* marker, void* data,
 
   // new or updated document
   if (type == TRI_DF_MARKER_VPACK_DOCUMENT) {
-    VPackSlice const slice(reinterpret_cast<char const*>(marker) + DatafileHelper::VPackOffset(type));
+    VPackSlice slice(reinterpret_cast<char const*>(marker) + DatafileHelper::VPackOffset(type));
     TRI_ASSERT(slice.isObject());
-    VPackSlice const keySlice(Transaction::extractKeyFromDocument(slice));
-    TRI_voc_rid_t const rid = std::stoull(slice.get(StaticStrings::RevString).copyString());
+
+    // use specialized conversion method for trusted input that does not 
+    // create a temporary std::string 
+    VPackSlice keySlice;
+    TRI_voc_rid_t rid;
+    Transaction::extractKeyAndRevFromDocument(slice, keySlice, rid);
 
     // check if the document is still active
     auto primaryIndex = document->primaryIndex();
diff --git a/arangod/Wal/CollectorThread.cpp b/arangod/Wal/CollectorThread.cpp
index 7ca2089fbe..24a1bfe091 100644
--- a/arangod/Wal/CollectorThread.cpp
+++ b/arangod/Wal/CollectorThread.cpp
@@ -49,19 +49,6 @@
 using namespace arangodb;
 using namespace arangodb::wal;
 
-/// @brief convert a slice value into its numeric equivalent
-template <typename T>
-static inline T NumericValue(VPackSlice const& slice, char const* attribute) {
-  VPackSlice v = slice.get(attribute);
-  if (v.isString()) {
-    return static_cast<T>(std::stoull(v.copyString()));
-  }
-  if (v.isNumber()) {
-    return v.getNumber<T>();
-  }
-  return 0;
-}
-
 /// @brief return a reference to an existing datafile statistics struct
 static inline DatafileStatisticsContainer& getDfi(CollectorCache* cache,
                                                   TRI_voc_fid_t fid) {