diff --git a/Tools/CodeGen/CalculationFunction.m b/Tools/CodeGen/CalculationFunction.m
index ee0ba6f..37b417a 100644
--- a/Tools/CodeGen/CalculationFunction.m
+++ b/Tools/CodeGen/CalculationFunction.m
@@ -126,7 +126,8 @@ replaceDerivatives[x_, derivRules_] :=
     x /. replaceStandard];
 
 (* Return a CodeGen block which assigns dest by evaluating expr *)
-assignVariableFromExpression[dest_, expr_] := Module[{tSym, type, cleanExpr, code},
+assignVariableFromExpression[dest_, expr_, declare_] :=
+  Module[{tSym, type, cleanExpr, code},
       
       tSym = Unique[];
       
@@ -135,7 +136,7 @@ assignVariableFromExpression[dest_, expr_] := Module[{tSym, type, cleanExpr, cod
       cleanExpr = ReplacePowers[expr] /. sym`t -> tSym;
   
       If[SOURCELANGUAGE == "C",
-        code = type <> " const " <>
+        code = If[declare, type <> " const ", ""] <>
                ToString[dest == cleanExpr, CForm,       PageWidth -> 120] <> ";\n",
         code = ToString@dest <> ".eq." <> ToString[cleanExpr, FortranForm, PageWidth -> 120] <> "\n"
        ];
@@ -294,6 +295,14 @@ simplifyEquationList[eqs_] :=
 simplifyEquation[lhs_ -> rhs_] :=
   lhs -> Simplify[rhs];
   
+(* Given an input list l, return a list L such that L[[i]] is True
+   only if l[[i]] is the first occurrence of l[[i]] in l and is not in
+   the list "already" *)
+markFirst[l_List, already_List] :=
+  If[l =!= {},
+    {!MemberQ[already, First[l]]} ~Join~ markFirst[Rest[l], already ~Join~ {First[l]}],
+    {}];
+
 VerifyListContent[l_, type_, while_] :=
   Module[{types},
     If[!(Head[l] === List),
@@ -656,7 +665,7 @@ equationLoop[eqs_,
              pddefs_, where_, addToStencilWidth_, useLoopControl_, useCSE_] :=
   Module[{rhss, lhss, gfsInRHS, gfsInLHS, gfsOnlyInRHS, localGFs, localMap, eqs2,
           derivSwitch, actualSyncGroups, code, functionName, calcCode,
-          syncCode, loopFunction},
+          syncCode, loopFunction, eqsReplaced, declare},
 
     rhss = Map[#[[2]] &, eqs];
     lhss = Map[#[[1]] &, eqs];
@@ -688,8 +697,24 @@ equationLoop[eqs_,
     eqs2 = ReplaceDerivatives[defsWithShorts, eqs2, False];
 
     checkEquationAssignmentOrder[eqs2, shorts];
-   code = {(*InitialiseGridLoopVariables[derivSwitch, addToStencilWidth], *)
-   functionName = ToString@lookup[cleancalc, Name];
+    code = {(*InitialiseGridLoopVariables[derivSwitch, addToStencilWidth], *)
+    functionName = ToString@lookup[cleancalc, Name];
+
+    (* Replace grid functions with their local forms *)
+    eqsReplaced = eqs2 /. localMap;
+
+    If[useCSE,
+      eqsReplaced = CSE[eqsReplaced]];
+
+    (* Construct a list, corresponding to the list of equations,
+       marking those which need their LHS variables declared.  We
+       declare variables at the same time as assigning to them as it
+       gives a performance increase over declaring them separately at
+       the start of the loop.  The local variables for the grid
+       functions which appear in the RHSs have been declared and set
+       already (DeclareMaybeAssignVariableInLoop below), so assignments
+       to these do not generate declarations here. *)
+    declare = markFirst[First /@ eqsReplaced, Map[localName, gfsInRHS]];
 
 (*
    calcCode =
@@ -697,11 +722,16 @@ equationLoop[eqs_,
            replaceDerivatives[replaceWithDerivativesHidden[eqs2, localMap], {}]
         ];
 *)
+(*
    calcCode =
      Map[{assignVariableFromExpression[#[[1]], #[[2]]], "\n"} &,
          If[useCSE, CSE, Identity][
            replaceDerivatives[replaceWithDerivativesHidden[eqs2, localMap], {}]]
         ];
+*)
+    calcCode =
+      MapThread[{assignVariableFromExpression[#1[[1]], #1[[2]], #2], "\n"} &,
+       {eqsReplaced, declare}];
 
    Join[
    (*
@@ -728,7 +758,7 @@ equationLoop[eqs_,
                           "CCTK_REAL", localName[#], GridName[#],
                           StringMatchQ[ToString[GridName[#]], "eT" ~~ _ ~~ _ ~~ "[" ~~ __ ~~ "]"],
                           "*stress_energy_state"] &,
-                       gfsOnlyInRHS]],
+                       (* gfsOnlyInRHS *) gfsInRHS]],
 
 (*
     CommentedBlock["Check for nans",
diff --git a/Tools/CodeGen/CodeGen.m b/Tools/CodeGen/CodeGen.m
index 2945d2b..d2d3ccb 100644
--- a/Tools/CodeGen/CodeGen.m
+++ b/Tools/CodeGen/CodeGen.m
@@ -294,8 +294,8 @@ MaybeAssignVariableInLoop[dest_, src_, cond_] :=
 
 DeclareMaybeAssignVariableInLoop[type_, dest_, src_, mmaCond_, codeCond_] :=
   If [mmaCond,
-      {type, " const ", dest, " = (", codeCond, ") ? (", src, ") : 0.0", EOL[]},
-      {type, " const ", dest, " = ", src, EOL[]}];
+      {type, " ", dest, " = (", codeCond, ") ? (", src, ") : 0.0", EOL[]},
+      {type, " ", dest, " = ", src, EOL[]}];
 
 (* TODO: move these into OpenMP loop *)
 DeclareVariablesInLoopVectorised[dests_, temps_, srcs_] :=