diff --git a/Expressions/FunctionCall.cs b/Expressions/FunctionCall.cs
index 258cac17..3b960feb 100644
--- a/Expressions/FunctionCall.cs
+++ b/Expressions/FunctionCall.cs
@@ -107,11 +107,16 @@ public void GatherMatchingFunctionCalls(ICollection<FunctionCall> matchingFuncti
             }
         }
 
+        private IMathObject[] _evaledArgsCache = new IMathObject[0];
+        // Warning: Not thread-safe
         public virtual IMathObject Call(SolusEnvironment env)
         {
-            var evaledArgs =
-                Arguments.Select(a => a.Eval(env)).ToArray();
-            return Function.Call(env, evaledArgs);
+            if (_evaledArgsCache.Length < Arguments.Count)
+                _evaledArgsCache = new IMathObject[Arguments.Count];
+            int i;
+            for (i = 0; i < Arguments.Count; i++)
+                _evaledArgsCache[i] = Arguments[i].Eval(env);
+            return Function.Call(env, _evaledArgsCache);
         }
 
         public virtual List<Expression> Arguments
diff --git a/Expressions/Literal.cs b/Expressions/Literal.cs
index 53f0619a..471b58f5 100644
--- a/Expressions/Literal.cs
+++ b/Expressions/Literal.cs
@@ -76,7 +76,7 @@ public virtual IMathObject Value
                 if (_value != value)
 				{
                     _value = value;
-					this.OnValueChanged(new EventArgs());
+					this.OnValueChanged(EventArgs.Empty);
 				}
 			}
 		}
diff --git a/Expressions/VariableAccess.cs b/Expressions/VariableAccess.cs
index d4435ecb..63cbec31 100644
--- a/Expressions/VariableAccess.cs
+++ b/Expressions/VariableAccess.cs
@@ -55,7 +55,7 @@ public override IMathObject Eval(SolusEnvironment env)
             if (env.ContainsVariable(var))
             {
                 if (env.GetVariable(var) is Literal literal)
-                    return literal.Value.ToNumber();
+                    return literal.Value;
 
                 return env.GetVariable(var).Eval(env);
             }
diff --git a/Expressions/VectorExpression.cs b/Expressions/VectorExpression.cs
index 40519fa9..fbd043e2 100644
--- a/Expressions/VectorExpression.cs
+++ b/Expressions/VectorExpression.cs
@@ -101,7 +101,8 @@ public override IMathObject Eval(SolusEnvironment env)
             var values = new IMathObject[Length];
             for (int i = 0; i < Length; i++)
                 values[i] = this[i].Eval(env);
-            return new Vector(values);
+            // Vector will take ownership of array
+            return new Vector(values);  // TODO: don't box here
         }
 
         public override Expression Clone()
@@ -214,19 +215,30 @@ public override void AcceptVisitor(IExpressionVisitor visitor)
             }
         }
 
+        private Expression[] _valuesCache = null;
         public override Expression PreliminaryEval(SolusEnvironment env)
         {
-            var values = _array.Select(
-                e => e.PreliminaryEval(env)).ToArray();
-            if (values.All(e => e is Literal))
+            if (_valuesCache == null ||
+                _valuesCache.Length < _array.Length)
+                _valuesCache = new Expression[_array.Length];
+
+            bool allLiterals = true;
+            int i;
+            for (i = 0; i < _array.Length; i++)
+            {
+                var e = _valuesCache[i] = _array[i].PreliminaryEval(env);
+                allLiterals &= e is Literal;
+            }
+            if (allLiterals)
             {
-                return new Literal(
-                    new Vector(
-                        values.Select(
-                            e => ((Literal) e).Value).ToArray()));
+                var values = new IMathObject[_valuesCache.Length];
+                for (i = 0; i < _array.Length; i++)
+                    values[i] = ((Literal)_valuesCache[i]).Value;
+                // Vector will take ownership of array
+                return new Literal(new Vector(values));
             }
 
-            return new VectorExpression(values.Length, values);
+            return new VectorExpression(_valuesCache.Length, _valuesCache);
         }
 
         public override void ApplyToAll(Modulator mod)
diff --git a/Values/Vector.cs b/Values/Vector.cs
index 60956fe4..c7535a05 100644
--- a/Values/Vector.cs
+++ b/Values/Vector.cs
@@ -29,6 +29,7 @@ namespace MetaphysicsIndustries.Solus.Values
     {
         public Vector(IMathObject[] components)
         {
+            // TODO: don't clone here
             _components = (IMathObject[]) components.Clone();
 
             var componentType = _components[0].GetMathType();