diff --git a/tool/src/org/antlr/v4/codegen/Target.java b/tool/src/org/antlr/v4/codegen/Target.java
index 618d891a21..2f6b6f522d 100644
--- a/tool/src/org/antlr/v4/codegen/Target.java
+++ b/tool/src/org/antlr/v4/codegen/Target.java
@@ -18,12 +18,7 @@
 import org.antlr.v4.tool.Grammar;
 import org.antlr.v4.tool.Rule;
 import org.antlr.v4.tool.ast.GrammarAST;
-import org.stringtemplate.v4.NumberRenderer;
-import org.stringtemplate.v4.ST;
-import org.stringtemplate.v4.STErrorListener;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.STGroupFile;
-import org.stringtemplate.v4.StringRenderer;
+import org.stringtemplate.v4.*;
 import org.stringtemplate.v4.misc.STMessage;
 
 import java.util.HashMap;
@@ -32,8 +27,9 @@
 
 /** */
 public abstract class Target {
+	private final static Map<String, STGroup> languageTemplates = new HashMap<>();
+
 	protected final CodeGenerator gen;
-	private STGroup templates;
 
 	protected static final Map<Character, String> defaultCharValueEscape;
 	static {
@@ -92,14 +88,22 @@ public String getVersion() {
 	}
 
 	public STGroup getTemplates() {
+		String language = getLanguage();
+		STGroup templates = languageTemplates.get(language);
+
 		if (templates == null) {
-			String version = getVersion();
-			if ( version==null ||
-				 !RuntimeMetaData.getMajorMinorVersion(version).equals(RuntimeMetaData.getMajorMinorVersion(Tool.VERSION)))
-			{
-				gen.tool.errMgr.toolError(ErrorType.INCOMPATIBLE_TOOL_AND_TEMPLATES, version, Tool.VERSION, getLanguage());
+			synchronized (languageTemplates) {
+				templates = languageTemplates.get(language);
+				if (templates == null) {
+					String version = getVersion();
+					if (version == null ||
+							!RuntimeMetaData.getMajorMinorVersion(version).equals(RuntimeMetaData.getMajorMinorVersion(Tool.VERSION))) {
+						gen.tool.errMgr.toolError(ErrorType.INCOMPATIBLE_TOOL_AND_TEMPLATES, version, Tool.VERSION, language);
+					}
+					templates = loadTemplates();
+					languageTemplates.put(language, templates);
+				}
 			}
-			templates = loadTemplates();
 		}
 
 		return templates;
diff --git a/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java b/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
index 3d15c1cb14..c6212df68f 100644
--- a/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
@@ -136,41 +136,6 @@ protected String escapeWord(String word) {
 		return "@" + word;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		// override the superclass behavior to put all C# templates in the same folder
-		STGroup result = new STGroupFile(CodeGenerator.TEMPLATE_ROOT+"/CSharp/"+ getLanguage()+STGroup.GROUP_FILE_EXTENSION);
-		result.registerRenderer(Integer.class, new NumberRenderer());
-		result.registerRenderer(String.class, new StringRenderer());
-		result.setListener(new STErrorListener() {
-			@Override
-			public void compileTimeError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void runTimeError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void IOError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void internalError(STMessage msg) {
-				reportError(msg);
-			}
-
-			private void reportError(STMessage msg) {
-				getCodeGenerator().tool.errMgr.toolError(ErrorType.STRING_TEMPLATE_WARNING, msg.cause, msg.toString());
-			}
-		});
-
-		return result;
-	}
-
 	@Override
 	public boolean isATNSerializedAsInts() {
 		return true;
diff --git a/tool/src/org/antlr/v4/codegen/target/CppTarget.java b/tool/src/org/antlr/v4/codegen/target/CppTarget.java
index d5cc5fff57..f8fc4d2702 100644
--- a/tool/src/org/antlr/v4/codegen/target/CppTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/CppTarget.java
@@ -8,14 +8,7 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.antlr.v4.tool.ErrorType;
-import org.stringtemplate.v4.NumberRenderer;
 import org.stringtemplate.v4.ST;
-import org.stringtemplate.v4.STErrorListener;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
-import org.stringtemplate.v4.misc.STMessage;
-
 import java.util.*;
 
 public class CppTarget extends Target {
@@ -124,38 +117,4 @@ public String getBaseVisitorFileName(boolean header) {
 		String listenerName = gen.g.name + "BaseVisitor";
 		return listenerName+extST.render();
 	}
-
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(Integer.class, new NumberRenderer());
-		result.registerRenderer(String.class, new StringRenderer());
-		result.setListener(new STErrorListener() {
-			@Override
-			public void compileTimeError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void runTimeError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void IOError(STMessage msg) {
-				reportError(msg);
-			}
-
-			@Override
-			public void internalError(STMessage msg) {
-				reportError(msg);
-			}
-
-			private void reportError(STMessage msg) {
-				getCodeGenerator().tool.errMgr.toolError(ErrorType.STRING_TEMPLATE_WARNING, msg.cause, msg.toString());
-			}
-		});
-
-		return result;
-	}
 }
diff --git a/tool/src/org/antlr/v4/codegen/target/DartTarget.java b/tool/src/org/antlr/v4/codegen/target/DartTarget.java
index 64dc2ee3b5..30e1209f63 100644
--- a/tool/src/org/antlr/v4/codegen/target/DartTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/DartTarget.java
@@ -8,18 +8,13 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.*;
 
 public class DartTarget extends Target {
 	protected static final Map<Character, String> targetCharValueEscape;
 	static {
-		HashMap<Character, String> map = new HashMap<>();
-		for (Map.Entry<Character, String> entry : defaultCharValueEscape.entrySet()) {
-			map.put(entry.getKey(), entry.getValue());
-		}
+		HashMap<Character, String> map = new HashMap<>(defaultCharValueEscape);
 		addEscapedChar(map, '$');
 		targetCharValueEscape = map;
 	}
@@ -63,14 +58,6 @@ public Set<String> getReservedWords() {
 		return reservedWords;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new StringRenderer(), true);
-
-		return result;
-	}
-
 	@Override
 	public boolean isATNSerializedAsInts() {
 		return true;
diff --git a/tool/src/org/antlr/v4/codegen/target/GoTarget.java b/tool/src/org/antlr/v4/codegen/target/GoTarget.java
index 21eb79fc4d..672507883b 100644
--- a/tool/src/org/antlr/v4/codegen/target/GoTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/GoTarget.java
@@ -99,13 +99,6 @@ public int getInlineTestSetWordSize() {
 		return 32;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new JavaStringRenderer(), true);
-		return result;
-	}
-
 	public String getRecognizerFileName(boolean header) {
 		CodeGenerator gen = getCodeGenerator();
 		Grammar g = gen.g;
@@ -164,17 +157,4 @@ public String getBaseVisitorFileName(boolean header) {
 		assert g.name != null;
 		return g.name.toLowerCase()+"_base_visitor.go";
 	}
-
-	protected static class JavaStringRenderer extends StringRenderer {
-		@Override
-		public String toString(Object o, String formatString, Locale locale) {
-
-			if ("java-escape".equals(formatString)) {
-				// 5C is the hex code for the \ itself
-				return ((String)o).replace("\\u", "\\u005Cu");
-			}
-
-			return super.toString(o, formatString, locale);
-		}
-	}
 }
diff --git a/tool/src/org/antlr/v4/codegen/target/JavaScriptTarget.java b/tool/src/org/antlr/v4/codegen/target/JavaScriptTarget.java
index d199f3ed5f..ae30501414 100644
--- a/tool/src/org/antlr/v4/codegen/target/JavaScriptTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/JavaScriptTarget.java
@@ -8,13 +8,9 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.antlr.v4.tool.ast.GrammarAST;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.Arrays;
 import java.util.HashSet;
-import java.util.Locale;
 import java.util.Set;
 
 public class JavaScriptTarget extends Target {
@@ -56,27 +52,6 @@ public int getInlineTestSetWordSize() {
 		return 32;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new JavaStringRenderer(), true);
-		return result;
-	}
-
-	protected static class JavaStringRenderer extends StringRenderer {
-
-		@Override
-		public String toString(Object o, String formatString, Locale locale) {
-			if ("java-escape".equals(formatString)) {
-				// 5C is the hex code for the \ itself
-				return ((String)o).replace("\\u", "\\u005Cu");
-			}
-
-			return super.toString(o, formatString, locale);
-		}
-
-	}
-
 	@Override
 	public boolean wantsBaseListener() {
 		return false;
diff --git a/tool/src/org/antlr/v4/codegen/target/JavaTarget.java b/tool/src/org/antlr/v4/codegen/target/JavaTarget.java
index 869c98e445..4b1a12b7c7 100644
--- a/tool/src/org/antlr/v4/codegen/target/JavaTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/JavaTarget.java
@@ -49,31 +49,6 @@ public int getSerializedATNSegmentLimit() {
 		return 65535 / 3;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = targetTemplates.get();
-		if (result == null) {
-			result = super.loadTemplates();
-			result.registerRenderer(String.class, new JavaStringRenderer(), true);
-			targetTemplates.set(result);
-		}
-
-		return result;
-	}
-
-	protected static class JavaStringRenderer extends StringRenderer {
-
-		@Override
-		public String toString(Object o, String formatString, Locale locale) {
-			if ("java-escape".equals(formatString)) {
-				// 5C is the hex code for the \ itself
-				return ((String)o).replace("\\u", "\\u005Cu");
-			}
-
-			return super.toString(o, formatString, locale);
-		}
-	}
-
 	@Override
 	public boolean isATNSerializedAsInts() {
 		return false;
diff --git a/tool/src/org/antlr/v4/codegen/target/PHPTarget.java b/tool/src/org/antlr/v4/codegen/target/PHPTarget.java
index b8c362f2f6..4f9188df3b 100644
--- a/tool/src/org/antlr/v4/codegen/target/PHPTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/PHPTarget.java
@@ -8,8 +8,6 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.*;
 
@@ -73,14 +71,6 @@ protected Set<String> getReservedWords() {
 		return reservedWords;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new StringRenderer(), true);
-
-		return result;
-	}
-
 	@Override
 	public boolean supportsOverloadedMethods() {
 		return false;
diff --git a/tool/src/org/antlr/v4/codegen/target/Python2Target.java b/tool/src/org/antlr/v4/codegen/target/Python2Target.java
index 6f4ac59041..9efa20f448 100644
--- a/tool/src/org/antlr/v4/codegen/target/Python2Target.java
+++ b/tool/src/org/antlr/v4/codegen/target/Python2Target.java
@@ -8,8 +8,6 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.*;
 
@@ -76,21 +74,6 @@ protected Set<String> getReservedWords() {
 		return reservedWords;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new PythonStringRenderer(), true);
-		return result;
-	}
-
-	protected static class PythonStringRenderer extends StringRenderer {
-
-		@Override
-		public String toString(Object o, String formatString, Locale locale) {
-			return super.toString(o, formatString, locale);
-		}
-	}
-
 	@Override
 	public boolean wantsBaseListener() {
 		return false;
diff --git a/tool/src/org/antlr/v4/codegen/target/Python3Target.java b/tool/src/org/antlr/v4/codegen/target/Python3Target.java
index c4684cc68b..768dbc1ef7 100644
--- a/tool/src/org/antlr/v4/codegen/target/Python3Target.java
+++ b/tool/src/org/antlr/v4/codegen/target/Python3Target.java
@@ -8,8 +8,6 @@
 
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.*;
 
@@ -75,21 +73,6 @@ protected Set<String> getReservedWords() {
 		return reservedWords;
 	}
 
-	@Override
-	protected STGroup loadTemplates() {
-		STGroup result = super.loadTemplates();
-		result.registerRenderer(String.class, new PythonStringRenderer(), true);
-		return result;
-	}
-
-	protected static class PythonStringRenderer extends StringRenderer {
-
-		@Override
-		public String toString(Object o, String formatString, Locale locale) {
-			return super.toString(o, formatString, locale);
-		}
-	}
-
 	@Override
 	public boolean wantsBaseListener() {
 		return false;
diff --git a/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java b/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
index aee548b335..320bc786df 100644
--- a/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
@@ -10,22 +10,14 @@
 import org.antlr.v4.codegen.Target;
 import org.antlr.v4.tool.Grammar;
 import org.stringtemplate.v4.ST;
-import org.stringtemplate.v4.STGroup;
-import org.stringtemplate.v4.StringRenderer;
 
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
 public class SwiftTarget extends Target {
-    /**
-     * The Swift target can cache the code generation templates.
-     */
-    private static final ThreadLocal<STGroup> targetTemplates = new ThreadLocal<>();
-
 	protected static final Map<Character, String> targetCharValueEscape;
 	static {
 		// https://docs.swift.org/swift-book/LanguageGuide/StringsAndCharacters.html
@@ -78,30 +70,6 @@ protected void genFile(Grammar g, ST outputFileST, String fileName) {
         super.genFile(g,outputFileST,fileName);
     }
 
-    @Override
-    protected STGroup loadTemplates() {
-        STGroup result = targetTemplates.get();
-        if (result == null) {
-            result = super.loadTemplates();
-            result.registerRenderer(String.class, new SwiftStringRenderer(), true);
-            targetTemplates.set(result);
-        }
-
-        return result;
-    }
-
-    protected static class SwiftStringRenderer extends StringRenderer {
-        @Override
-        public String toString(Object o, String formatString, Locale locale) {
-            if ("java-escape".equals(formatString)) {
-                // 5C is the hex code for the \ itself
-                return ((String)o).replace("\\u", "\\u005Cu");
-            }
-
-            return super.toString(o, formatString, locale);
-        }
-    }
-
 	@Override
 	public boolean isATNSerializedAsInts() {
 		return true;