diff -r e59349d53fec -r 1725fdb6c4f5 src/goodjava/util/GoodUtils.java
--- a/src/goodjava/util/GoodUtils.java	Thu Aug 10 16:24:20 2023 -0600
+++ b/src/goodjava/util/GoodUtils.java	Fri Aug 11 10:44:56 2023 -0600
@@ -69,4 +69,22 @@
 		return list.subList(0, resultSize).toArray(result);
 	}
 
+	// faster than String.replace()
+	public static String replace(String s,String target,String replacement) {
+		int i = s.indexOf(target);
+		if( i == -1 )
+			return s;
+		int starting = 0;
+		int n = target.length();
+		StringBuilder sb = new StringBuilder();
+		do {
+			sb.append(s,starting,i);
+			sb.append(replacement);
+			starting = i + n;
+			i = s.indexOf(target,starting);
+		} while( i != -1 );
+		sb.append(s,starting,s.length());
+		return sb.toString();
+	}
+
 }

diff -r e59349d53fec -r 1725fdb6c4f5 src/luan/modules/StringLuan.java
--- a/src/luan/modules/StringLuan.java	Thu Aug 10 16:24:20 2023 -0600
+++ b/src/luan/modules/StringLuan.java	Fri Aug 11 10:44:56 2023 -0600
@@ -148,32 +148,12 @@
 		Utils.checkNotNull(s2,2);
 		return s.endsWith(s2);
 	}
-/*
-	public static String replace(String s,String target,String replacement) throws LuanException {
-		Utils.checkNotNull(s);
-		Utils.checkNotNull(target,2);
-		Utils.checkNotNull(replacement,3);
-		return s.replace(target,replacement);
-	}
-*/
+
 	public static String replace(String s,String target,String replacement) throws LuanException {
 		Utils.checkNotNull(s);
 		Utils.checkNotNull(target,2);
 		Utils.checkNotNull(replacement,3);
-		int i = s.indexOf(target);
-		if( i == -1 )
-			return s;
-		int starting = 0;
-		int n = target.length();
-		StringBuilder sb = new StringBuilder();
-		do {
-			sb.append(s,starting,i);
-			sb.append(replacement);
-			starting = i + n;
-			i = s.indexOf(target,starting);
-		} while( i != -1 );
-		sb.append(s,starting,s.length());
-		return sb.toString();
+		return GoodUtils.replace(s,target,replacement);
 	}
 
 }