diff --git a/content/base/src/nsStyleSet.cpp b/content/base/src/nsStyleSet.cpp
index 23199b460e5..7472ff0ddb1 100644
--- a/content/base/src/nsStyleSet.cpp
+++ b/content/base/src/nsStyleSet.cpp
@@ -36,7 +36,14 @@
 #include "nsLayoutAtoms.h"
 #include "nsTimer.h"
 #ifdef MOZ_PERF_METRICS
-#include "nsITimeRecorder.h"
+  #include "nsITimeRecorder.h"
+  #define STYLESET_START_TIMER(a) \
+    StartTimer(a)
+  #define STYLESET_STOP_TIMER(a) \
+    StopTimer(a)
+#else
+  #define STYLESET_START_TIMER(a) ((void)0)
+  #define STYLESET_STOP_TIMER(a) ((void)0)
 #endif
 
 static NS_DEFINE_IID(kIStyleSetIID, NS_ISTYLE_SET_IID);
@@ -201,6 +208,11 @@ protected:
   nsIStyleFrameConstruction* mFrameConstructor;
 
   MOZ_TIMER_DECLARE(mStyleResolutionWatch)
+
+#ifdef MOZ_PERF_METRICS
+  PRBool            mTimerEnabled;   // true if timing is enabled, false if disabled
+#endif
+
 };
 
 StyleSetImpl::StyleSetImpl()
@@ -210,6 +222,9 @@ StyleSetImpl::StyleSetImpl()
     mRuleProcessors(nsnull),
     mRecycler(nsnull),
     mFrameConstructor(nsnull)
+#ifdef MOZ_PERF_METRICS
+    ,mTimerEnabled(PR_FALSE)
+#endif
 {
   NS_INIT_REFCNT();
 }
@@ -620,7 +635,8 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
                                                PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aContent, "must have content");
@@ -664,7 +680,7 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -710,7 +726,8 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
                                                      PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -756,7 +773,7 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -767,7 +784,8 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
                                                    PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -812,7 +830,7 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
   }
   
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -1105,6 +1123,52 @@ NS_NewStyleSet(nsIStyleSet** aInstancePtrResult)
 // nsITimeRecorder implementation
 
 #ifdef MOZ_PERF_METRICS
+
+NS_IMETHODIMP
+StyleSetImpl::EnableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_TRUE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::DisableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_FALSE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::IsTimerEnabled(PRBool *aIsEnabled, PRUint32 aTimerID)
+{
+  NS_ASSERTION(aIsEnabled != nsnull, "aIsEnabled paramter cannot be null" );
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+	  if (*aIsEnabled != nsnull) {
+      *aIsEnabled = mTimerEnabled;		
+	  }
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
 NS_IMETHODIMP
 StyleSetImpl::ResetTimer(PRUint32 aTimerID)
 {
@@ -1125,7 +1189,14 @@ StyleSetImpl::StartTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_START(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_START(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to start timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;
@@ -1139,7 +1210,14 @@ StyleSetImpl::StopTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_STOP(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_STOP(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to stop timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;
diff --git a/layout/base/src/nsStyleSet.cpp b/layout/base/src/nsStyleSet.cpp
index 23199b460e5..7472ff0ddb1 100644
--- a/layout/base/src/nsStyleSet.cpp
+++ b/layout/base/src/nsStyleSet.cpp
@@ -36,7 +36,14 @@
 #include "nsLayoutAtoms.h"
 #include "nsTimer.h"
 #ifdef MOZ_PERF_METRICS
-#include "nsITimeRecorder.h"
+  #include "nsITimeRecorder.h"
+  #define STYLESET_START_TIMER(a) \
+    StartTimer(a)
+  #define STYLESET_STOP_TIMER(a) \
+    StopTimer(a)
+#else
+  #define STYLESET_START_TIMER(a) ((void)0)
+  #define STYLESET_STOP_TIMER(a) ((void)0)
 #endif
 
 static NS_DEFINE_IID(kIStyleSetIID, NS_ISTYLE_SET_IID);
@@ -201,6 +208,11 @@ protected:
   nsIStyleFrameConstruction* mFrameConstructor;
 
   MOZ_TIMER_DECLARE(mStyleResolutionWatch)
+
+#ifdef MOZ_PERF_METRICS
+  PRBool            mTimerEnabled;   // true if timing is enabled, false if disabled
+#endif
+
 };
 
 StyleSetImpl::StyleSetImpl()
@@ -210,6 +222,9 @@ StyleSetImpl::StyleSetImpl()
     mRuleProcessors(nsnull),
     mRecycler(nsnull),
     mFrameConstructor(nsnull)
+#ifdef MOZ_PERF_METRICS
+    ,mTimerEnabled(PR_FALSE)
+#endif
 {
   NS_INIT_REFCNT();
 }
@@ -620,7 +635,8 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
                                                PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aContent, "must have content");
@@ -664,7 +680,7 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -710,7 +726,8 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
                                                      PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -756,7 +773,7 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -767,7 +784,8 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
                                                    PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -812,7 +830,7 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
   }
   
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -1105,6 +1123,52 @@ NS_NewStyleSet(nsIStyleSet** aInstancePtrResult)
 // nsITimeRecorder implementation
 
 #ifdef MOZ_PERF_METRICS
+
+NS_IMETHODIMP
+StyleSetImpl::EnableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_TRUE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::DisableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_FALSE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::IsTimerEnabled(PRBool *aIsEnabled, PRUint32 aTimerID)
+{
+  NS_ASSERTION(aIsEnabled != nsnull, "aIsEnabled paramter cannot be null" );
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+	  if (*aIsEnabled != nsnull) {
+      *aIsEnabled = mTimerEnabled;		
+	  }
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
 NS_IMETHODIMP
 StyleSetImpl::ResetTimer(PRUint32 aTimerID)
 {
@@ -1125,7 +1189,14 @@ StyleSetImpl::StartTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_START(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_START(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to start timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;
@@ -1139,7 +1210,14 @@ StyleSetImpl::StopTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_STOP(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_STOP(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to stop timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;
diff --git a/layout/style/nsStyleSet.cpp b/layout/style/nsStyleSet.cpp
index 23199b460e5..7472ff0ddb1 100644
--- a/layout/style/nsStyleSet.cpp
+++ b/layout/style/nsStyleSet.cpp
@@ -36,7 +36,14 @@
 #include "nsLayoutAtoms.h"
 #include "nsTimer.h"
 #ifdef MOZ_PERF_METRICS
-#include "nsITimeRecorder.h"
+  #include "nsITimeRecorder.h"
+  #define STYLESET_START_TIMER(a) \
+    StartTimer(a)
+  #define STYLESET_STOP_TIMER(a) \
+    StopTimer(a)
+#else
+  #define STYLESET_START_TIMER(a) ((void)0)
+  #define STYLESET_STOP_TIMER(a) ((void)0)
 #endif
 
 static NS_DEFINE_IID(kIStyleSetIID, NS_ISTYLE_SET_IID);
@@ -201,6 +208,11 @@ protected:
   nsIStyleFrameConstruction* mFrameConstructor;
 
   MOZ_TIMER_DECLARE(mStyleResolutionWatch)
+
+#ifdef MOZ_PERF_METRICS
+  PRBool            mTimerEnabled;   // true if timing is enabled, false if disabled
+#endif
+
 };
 
 StyleSetImpl::StyleSetImpl()
@@ -210,6 +222,9 @@ StyleSetImpl::StyleSetImpl()
     mRuleProcessors(nsnull),
     mRecycler(nsnull),
     mFrameConstructor(nsnull)
+#ifdef MOZ_PERF_METRICS
+    ,mTimerEnabled(PR_FALSE)
+#endif
 {
   NS_INIT_REFCNT();
 }
@@ -620,7 +635,8 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
                                                PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aContent, "must have content");
@@ -664,7 +680,7 @@ nsIStyleContext* StyleSetImpl::ResolveStyleFor(nsIPresContext* aPresContext,
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolveStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -710,7 +726,8 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
                                                      PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -756,7 +773,7 @@ nsIStyleContext* StyleSetImpl::ResolvePseudoStyleFor(nsIPresContext* aPresContex
   }
 
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ResolvePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -767,7 +784,8 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
                                                    PRBool aForceUnique)
 {
   MOZ_TIMER_DEBUGLOG(("Start: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_START(mStyleResolutionWatch);
+  STYLESET_START_TIMER(NS_TIMER_STYLE_RESOLUTION);
+
   nsIStyleContext*  result = nsnull;
 
   NS_ASSERTION(aPseudoTag, "must have pseudo tag");
@@ -812,7 +830,7 @@ nsIStyleContext* StyleSetImpl::ProbePseudoStyleFor(nsIPresContext* aPresContext,
   }
   
   MOZ_TIMER_DEBUGLOG(("Stop: StyleSetImpl::ProbePseudoStyleFor(), this=%p\n", this));
-  MOZ_TIMER_STOP(mStyleResolutionWatch);
+  STYLESET_STOP_TIMER(NS_TIMER_STYLE_RESOLUTION);
   return result;
 }
 
@@ -1105,6 +1123,52 @@ NS_NewStyleSet(nsIStyleSet** aInstancePtrResult)
 // nsITimeRecorder implementation
 
 #ifdef MOZ_PERF_METRICS
+
+NS_IMETHODIMP
+StyleSetImpl::EnableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_TRUE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::DisableTimer(PRUint32 aTimerID)
+{
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+    mTimerEnabled = PR_FALSE;
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
+NS_IMETHODIMP
+StyleSetImpl::IsTimerEnabled(PRBool *aIsEnabled, PRUint32 aTimerID)
+{
+  NS_ASSERTION(aIsEnabled != nsnull, "aIsEnabled paramter cannot be null" );
+  nsresult rv = NS_OK;
+
+  if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
+	  if (*aIsEnabled != nsnull) {
+      *aIsEnabled = mTimerEnabled;		
+	  }
+  }
+  else 
+    rv = NS_ERROR_NOT_IMPLEMENTED;
+  
+  return rv;
+}
+
 NS_IMETHODIMP
 StyleSetImpl::ResetTimer(PRUint32 aTimerID)
 {
@@ -1125,7 +1189,14 @@ StyleSetImpl::StartTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_START(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_START(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to start timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;
@@ -1139,7 +1210,14 @@ StyleSetImpl::StopTimer(PRUint32 aTimerID)
   nsresult rv = NS_OK;
 
   if (NS_TIMER_STYLE_RESOLUTION == aTimerID) {
-    MOZ_TIMER_STOP(mStyleResolutionWatch);
+    // only do it if enabled
+    if (mTimerEnabled) {
+      MOZ_TIMER_STOP(mStyleResolutionWatch);
+    } else {
+#ifdef _DEBUG
+      // printf( "Attempt to stop timer while disabled - ignoring\n" );
+#endif
+    }
   }
   else 
     rv = NS_ERROR_NOT_IMPLEMENTED;