diff --git a/src/main/java/dev/latvian/mods/rhino/JavaMembers.java b/src/main/java/dev/latvian/mods/rhino/JavaMembers.java
index 435c9b2f..cc4a90f5 100644
--- a/src/main/java/dev/latvian/mods/rhino/JavaMembers.java
+++ b/src/main/java/dev/latvian/mods/rhino/JavaMembers.java
@@ -24,6 +24,7 @@
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -580,7 +581,7 @@ private void reflect(Scriptable scope, boolean includeProtected, Context cx) {
 					char ch0 = nameComponent.charAt(0);
 					if (Character.isUpperCase(ch0)) {
 						if (nameComponent.length() == 1) {
-							beanPropertyName = nameComponent.toLowerCase();
+							beanPropertyName = nameComponent.toLowerCase(Locale.ROOT);
 						} else {
 							char ch1 = nameComponent.charAt(1);
 							if (!Character.isUpperCase(ch1)) {
diff --git a/src/main/java/dev/latvian/mods/rhino/NativeString.java b/src/main/java/dev/latvian/mods/rhino/NativeString.java
index e75e8f21..e00e3547 100644
--- a/src/main/java/dev/latvian/mods/rhino/NativeString.java
+++ b/src/main/java/dev/latvian/mods/rhino/NativeString.java
@@ -1004,11 +1004,11 @@ public Object execIdCall(IdFunctionObject f, Context cx, Scriptable scope, Scrip
 				}
 				case Id_toLocaleLowerCase: {
 					String thisStr = ScriptRuntime.toString(cx, ScriptRuntimeES6.requireObjectCoercible(cx, thisObj, f));
-					return thisStr.toLowerCase();
+					return thisStr.toLowerCase(Locale.ROOT);
 				}
 				case Id_toLocaleUpperCase: {
 					String thisStr = ScriptRuntime.toString(cx, ScriptRuntimeES6.requireObjectCoercible(cx, thisObj, f));
-					return thisStr.toUpperCase();
+					return thisStr.toUpperCase(Locale.ROOT);
 				}
 				case Id_trim: {
 					String str = ScriptRuntime.toString(cx, ScriptRuntimeES6.requireObjectCoercible(cx, thisObj, f));
diff --git a/src/main/java/dev/latvian/mods/rhino/ScriptableObject.java b/src/main/java/dev/latvian/mods/rhino/ScriptableObject.java
index 25d16ba0..591274d5 100644
--- a/src/main/java/dev/latvian/mods/rhino/ScriptableObject.java
+++ b/src/main/java/dev/latvian/mods/rhino/ScriptableObject.java
@@ -30,6 +30,7 @@
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Map;
 
 /**
@@ -757,7 +758,7 @@ private static String getPropertyName(String methodName, String prefix, Annotati
 					propName = methodName.substring(3);
 					if (Character.isUpperCase(propName.charAt(0))) {
 						if (propName.length() == 1) {
-							propName = propName.toLowerCase();
+							propName = propName.toLowerCase(Locale.ROOT);
 						} else if (!Character.isUpperCase(propName.charAt(1))) {
 							propName = Character.toLowerCase(propName.charAt(0)) + propName.substring(1);
 						}
diff --git a/src/main/java/dev/latvian/mods/rhino/ast/VariableDeclaration.java b/src/main/java/dev/latvian/mods/rhino/ast/VariableDeclaration.java
index cb78b52f..42d188f5 100644
--- a/src/main/java/dev/latvian/mods/rhino/ast/VariableDeclaration.java
+++ b/src/main/java/dev/latvian/mods/rhino/ast/VariableDeclaration.java
@@ -11,6 +11,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * A list of one or more var, const or let declarations.
@@ -129,6 +130,6 @@ public void setIsStatement(boolean isStatement) {
 	}
 
 	private String declTypeName() {
-		return Token.typeToName(type).toLowerCase();
+		return Token.typeToName(type).toLowerCase(Locale.ROOT);
 	}
 }
diff --git a/src/main/java/dev/latvian/mods/rhino/type/EnumTypeInfo.java b/src/main/java/dev/latvian/mods/rhino/type/EnumTypeInfo.java
index cb972298..6df2f9d5 100644
--- a/src/main/java/dev/latvian/mods/rhino/type/EnumTypeInfo.java
+++ b/src/main/java/dev/latvian/mods/rhino/type/EnumTypeInfo.java
@@ -4,8 +4,10 @@
 import dev.latvian.mods.rhino.util.RemappedEnumConstant;
 import dev.latvian.mods.rhino.util.wrap.TypeWrapperFactory;
 
+import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.stream.Collectors;
 
@@ -25,6 +27,7 @@ public static String getName(Object e) {
 	}
 
 	private List<Object> constants;
+	private Map<String, Object> constantMap;
 
 	EnumTypeInfo(Class<?> type) {
 		super(type);
@@ -48,21 +51,41 @@ public Object wrap(Context cx, Object from, TypeInfo target) {
 				return null;
 			}
 
-			for (var entry : enumConstants()) {
+			var constants = enumConstants();
+
+			if (constantMap == null) {
+				constantMap = new HashMap<>(constants.size());
+
+				for (var entry : constants) {
+					var name = getName(entry);
+					constantMap.put(name.toLowerCase(Locale.ROOT), entry);
+					constantMap.put(name, entry);
+				}
+			}
+
+			var lookup = constantMap.get(s);
+
+			if (lookup != null) {
+				return lookup;
+			}
+
+			for (var entry : constants) {
 				if (getName(entry).equalsIgnoreCase(s)) {
 					return entry;
 				}
 			}
 
-			throw new IllegalArgumentException("'" + s + "' is not a valid enum constant! Valid values are: " + enumConstants().stream().map(EnumTypeInfo::getName).map(s1 -> "'" + s1 + "'").collect(Collectors.joining(", ")));
+			throw new IllegalArgumentException("'" + s + "' is not a valid enum constant! Valid values are: " + constants.stream().map(EnumTypeInfo::getName).map(s1 -> "'" + s1 + "'").collect(Collectors.joining(", ")));
 		} else if (from instanceof Number) {
 			int index = ((Number) from).intValue();
 
-			if (index < 0 || index >= enumConstants().size()) {
-				throw new IllegalArgumentException(index + " is not a valid enum index! Valid values are: 0 - " + (enumConstants().size() - 1));
+			var constants = enumConstants();
+
+			if (index < 0 || index >= constants.size()) {
+				throw new IllegalArgumentException(index + " is not a valid enum index! Valid values are: 0 - " + (constants.size() - 1));
 			}
 
-			return enumConstants().get(index);
+			return constants.get(index);
 		}
 
 		return from;
diff --git a/src/main/java/dev/latvian/mods/rhino/util/DefaultValueTypeHint.java b/src/main/java/dev/latvian/mods/rhino/util/DefaultValueTypeHint.java
index 2f92da70..3893af5b 100644
--- a/src/main/java/dev/latvian/mods/rhino/util/DefaultValueTypeHint.java
+++ b/src/main/java/dev/latvian/mods/rhino/util/DefaultValueTypeHint.java
@@ -1,5 +1,7 @@
 package dev.latvian.mods.rhino.util;
 
+import java.util.Locale;
+
 public enum DefaultValueTypeHint {
 	STRING,
 	NUMBER,
@@ -10,7 +12,7 @@ public enum DefaultValueTypeHint {
 	public final String name;
 
 	DefaultValueTypeHint() {
-		name = name().toLowerCase();
+		name = name().toLowerCase(Locale.ROOT);
 	}
 
 	public String toString() {