diff --git a/xpcom/ds/nsFixedSizeAllocator.h b/xpcom/ds/nsFixedSizeAllocator.h
index a9424da7da6..248d660ccfe 100644
--- a/xpcom/ds/nsFixedSizeAllocator.h
+++ b/xpcom/ds/nsFixedSizeAllocator.h
@@ -156,9 +156,13 @@ protected:
     FindBucket(size_t aSize);
 
 public:
-    nsFixedSizeAllocator() : mBuckets(nsnull) {}
+    nsFixedSizeAllocator() : mBuckets(nsnull)
+    {
+        MOZ_COUNT_CTOR(nsFixedSizeAllocator);
+    }
 
     ~nsFixedSizeAllocator() {
+        MOZ_COUNT_DTOR(nsFixedSizeAllocator);
         if (mBuckets)
             PL_FinishArenaPool(&mPool);
     }
diff --git a/xpcom/ds/nsHashtable.cpp b/xpcom/ds/nsHashtable.cpp
index e36e8997560..e18e409f188 100644
--- a/xpcom/ds/nsHashtable.cpp
+++ b/xpcom/ds/nsHashtable.cpp
@@ -37,6 +37,7 @@
 #include "nsReadableUtils.h"
 #include "nsIObjectInputStream.h"
 #include "nsIObjectOutputStream.h"
+#include "plarena.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 // These functions really should be part of nspr, and have internal knowledge
@@ -164,6 +165,10 @@ static void PR_CALLBACK _hashFreeTable(void *pool, void *item) {
 }
 
 static PLHashEntry * PR_CALLBACK _hashAllocEntry(void *pool, const void *key) {
+    if (pool) {
+        return (PLHashEntry*)((nsFixedSizeAllocator*)pool)->Alloc(sizeof(PLHashEntry));
+    }
+    
     return PR_NEW(PLHashEntry);
 }
 
@@ -172,7 +177,11 @@ static void PR_CALLBACK _hashFreeEntry(void *pool, PLHashEntry *entry,
 {
     if (flag == HT_FREE_ENTRY) {
         delete (nsHashKey *) (entry->key);
-        PR_DELETE(entry);
+        if (pool) {
+            ((nsFixedSizeAllocator*)pool)->Free((void*)entry, sizeof(PLHashEntry));
+        }
+        else
+            PR_DELETE(entry);
     }
 }
 
@@ -220,13 +229,22 @@ nsHashtable::nsHashtable(PRUint32 aInitSize, PRBool threadSafe)
   : mLock(NULL), mEnumerating(PR_FALSE)
 {
     MOZ_COUNT_CTOR(nsHashtable);
+    
+    static const size_t kBucketSizes[] =
+        { sizeof(PLHashEntry) };
+    static const PRInt32 kNumBucketSizes =
+        sizeof(kBucketSizes) / sizeof(size_t);
+    
+    mPool.Init("hashFoo", kBucketSizes, kNumBucketSizes,
+               sizeof(PLHashEntry)*aInitSize);
+    
     PRStatus status = PL_HashTableInit(&mHashtable,
                                        aInitSize,
                                        _hashValue,
                                        _hashKeyCompare,
                                        _hashValueCompare,
                                        &_hashAllocOps,
-                                       NULL);
+                                       (void*)&mPool);
     PR_ASSERT(status == PR_SUCCESS);
     if (threadSafe) {
         mLock = PR_NewLock();
diff --git a/xpcom/ds/nsHashtable.h b/xpcom/ds/nsHashtable.h
index bf176b7b963..398e95ec93b 100644
--- a/xpcom/ds/nsHashtable.h
+++ b/xpcom/ds/nsHashtable.h
@@ -39,6 +39,8 @@
 #include "nsCom.h"
 #include "nsString.h"
 
+#include "nsFixedSizeAllocator.h"
+
 class nsIObjectInputStream;
 class nsIObjectOutputStream;
 
@@ -107,6 +109,7 @@ class NS_COM nsHashtable {
     PRLock*     mLock;
     PLHashTable mHashtable;
     PRBool      mEnumerating;
+    nsFixedSizeAllocator mPool;
 
   public:
     nsHashtable(PRUint32 aSize = 16, PRBool threadSafe = PR_FALSE);
diff --git a/xpcom/ds/nsStaticNameTable.cpp b/xpcom/ds/nsStaticNameTable.cpp
index 1d03ac04edb..7e9c3aaacc6 100644
--- a/xpcom/ds/nsStaticNameTable.cpp
+++ b/xpcom/ds/nsStaticNameTable.cpp
@@ -37,21 +37,16 @@
 #include "nscore.h"
 #include "nsString.h"
 #include "nsStaticNameTable.h"
-#include "nsReadableUtils.h"
 
 nsStaticCaseInsensitiveNameTable::nsStaticCaseInsensitiveNameTable()
-  : mNameArray(nsnull), mNameTable(nsnull), mCount(0), mNullStr("")
+    : mNameArray(nsnull), mNameTable(nsnull), mCount(0)
 {
     MOZ_COUNT_CTOR(nsStaticCaseInsensitiveNameTable);
 }  
 
 nsStaticCaseInsensitiveNameTable::~nsStaticCaseInsensitiveNameTable()
 {
-    // manually call the destructor on placement-new'ed objects
-    for (PRInt32 index = 0; index < mCount; index++) {
-      mNameArray[index].~nsDependentCString();
-    }
-    nsMemory::Free((void*)mNameArray);
+    delete [] mNameArray;
     delete mNameTable;
     MOZ_COUNT_DTOR(nsStaticCaseInsensitiveNameTable);
 }  
@@ -65,7 +60,7 @@ nsStaticCaseInsensitiveNameTable::Init(const char* Names[], PRInt32 Count)
     NS_ASSERTION(Count, "0 count");
 
     mCount = Count;
-    mNameArray = (nsDependentCString*)nsMemory::Alloc(Count * sizeof(nsDependentCString));
+    mNameArray = new nsCString[Count];
     // XXX best bucket count heuristic?
     mNameTable = new nsHashtable(Count<16 ? Count : Count<128 ? Count/4 : 128);
     if (!mNameArray || !mNameTable) {
@@ -75,18 +70,17 @@ nsStaticCaseInsensitiveNameTable::Init(const char* Names[], PRInt32 Count)
     for (PRInt32 index = 0; index < Count; ++index) {
         char*    raw = (char*) Names[index];
         PRUint32 len = nsCRT::strlen(raw);
+        nsStr*   str = NS_STATIC_CAST(nsStr*, &mNameArray[index]);
 #ifdef DEBUG
        {
        // verify invarients of contents
        nsCAutoString temp1(raw);
-       nsDependentCString temp2(raw);
+       nsCAutoString temp2(raw);
        temp1.ToLowerCase();
        NS_ASSERTION(temp1.Equals(temp2), "upper case char in table");
        }
-#endif
-       // use placement-new to initialize the string object
-       nsDependentCString *str =
-         new (&mNameArray[index]) nsDependentCString(raw);
+#endif      
+        nsStr::Initialize(*str, raw, len, len, eOneByte, PR_FALSE);
         nsCStringKey key(raw, len, nsCStringKey::NEVER_OWN);
         mNameTable->Put(&key, (void*)(index+1)); // to make 0 != nsnull
     }
@@ -94,7 +88,7 @@ nsStaticCaseInsensitiveNameTable::Init(const char* Names[], PRInt32 Count)
 }  
 
 inline PRInt32
-LookupLowercasedKeyword(const nsACString& aLowercasedKeyword, 
+LookupLowercasedKeyword(const nsCString& aLowercasedKeyword, 
                         nsHashtable* aTable)
 {
     nsCStringKey key(aLowercasedKeyword);
@@ -128,7 +122,7 @@ nsStaticCaseInsensitiveNameTable::Lookup(const nsAString& aName)
     return LookupLowercasedKeyword(strLower, mNameTable);
 }  
 
-const nsAFlatCString& 
+const nsCString& 
 nsStaticCaseInsensitiveNameTable::GetStringValue(PRInt32 index)
 {
     NS_ASSERTION(mNameArray, "not inited");