diff --git a/core/src/main/java/io/micronaut/core/util/StringUtils.java b/core/src/main/java/io/micronaut/core/util/StringUtils.java
index 78abd3b5468..ec1e77e08c9 100644
--- a/core/src/main/java/io/micronaut/core/util/StringUtils.java
+++ b/core/src/main/java/io/micronaut/core/util/StringUtils.java
@@ -366,18 +366,35 @@ public static String convertDotToUnderscore(String dottedProperty, boolean upper
      * @return A combined uri string
      */
     public static String prependUri(String baseUri, String uri) {
-        if (!uri.startsWith("/") && !uri.startsWith("?")) {
-            uri = "/" + uri;
+        StringBuilder builder = new StringBuilder(baseUri);
+        if (!uri.isEmpty() && (uri.length() != 1 || uri.charAt(0) != '/')) {
+            if (!uri.startsWith("/") && !uri.startsWith("?")) {
+                builder.append('/');
+            }
+            builder.append(uri);
+        }
+        if (builder.isEmpty()) {
+            return "";
         }
-        if (uri.length() == 1 && uri.charAt(0) == '/') {
-            uri = "";
+
+        int i = 0;
+        if (builder.charAt(0) != '/' && builder.indexOf("://") != -1) {
+            // skip until after scheme
+            while (i < builder.length() && builder.charAt(i) != ':') {
+                i++;
+            }
+            i += 2;
         }
-        uri = baseUri + uri;
-        if (uri.startsWith("/")) {
-            return uri.replaceAll("/{2,}", "/");
-        } else {
-            return uri.replaceAll("(?<=[^:])/{2,}", "/");
+        // replace double slashes
+        for (; i < builder.length() - 1; i++) {
+            if (builder.charAt(i) == '/' && builder.charAt(i + 1) == '/') {
+                builder.deleteCharAt(i);
+                i--;
+            } else if (builder.charAt(i) == '?') {
+                break;
+            }
         }
+        return builder.toString();
     }
 
     /**
diff --git a/http-client/src/main/java/io/micronaut/http/client/netty/DefaultHttpClient.java b/http-client/src/main/java/io/micronaut/http/client/netty/DefaultHttpClient.java
index 274a01739fd..22423b97a91 100644
--- a/http-client/src/main/java/io/micronaut/http/client/netty/DefaultHttpClient.java
+++ b/http-client/src/main/java/io/micronaut/http/client/netty/DefaultHttpClient.java
@@ -1284,14 +1284,14 @@ private NettyByteBody buildNettyRequest(
         boolean permitsBody,
         EventLoop eventLoop) throws HttpPostRequestEncoder.ErrorDataEncoderException {
 
-        if (!request.getHeaders().contains(io.micronaut.http.HttpHeaders.HOST)) {
+        if (!request.getHeaders().contains(HttpHeaderNames.HOST)) {
             request.getHeaders().set(HttpHeaderNames.HOST, getHostHeader(requestURI));
         }
 
         if (permitsBody) {
             Optional<?> body = request.getBody();
             if (body.isPresent()) {
-                if (!request.getHeaders().contains(io.micronaut.http.HttpHeaders.CONTENT_TYPE)) {
+                if (!request.getHeaders().contains(HttpHeaderNames.CONTENT_TYPE)) {
                     MediaType mediaType = request.getContentType().orElse(MediaType.APPLICATION_JSON_TYPE);
                     request.getHeaders().set(HttpHeaderNames.CONTENT_TYPE, mediaType);
                 }
@@ -1971,6 +1971,14 @@ private static MessageBodyHandlerRegistry createDefaultMessageBodyHandlerRegistr
     }
 
     static boolean isSecureScheme(String scheme) {
+        // fast path
+        if (scheme.equals("http")) {
+            return false;
+        }
+        if (scheme.equals("https")) {
+            return true;
+        }
+        // actual case-insensitive check
         return io.micronaut.http.HttpRequest.SCHEME_HTTPS.equalsIgnoreCase(scheme) || SCHEME_WSS.equalsIgnoreCase(scheme);
     }
 
diff --git a/http-netty/src/main/java/io/micronaut/http/netty/NettyHttpHeaders.java b/http-netty/src/main/java/io/micronaut/http/netty/NettyHttpHeaders.java
index 0c740ce15a1..55019ca132e 100644
--- a/http-netty/src/main/java/io/micronaut/http/netty/NettyHttpHeaders.java
+++ b/http-netty/src/main/java/io/micronaut/http/netty/NettyHttpHeaders.java
@@ -104,6 +104,11 @@ public final boolean contains(String name) {
         return nettyHeaders.contains(name);
     }
 
+    @Override
+    public final boolean contains(CharSequence name) {
+        return nettyHeaders.contains(name);
+    }
+
     @Override
     public <T> Optional<T> get(CharSequence name, ArgumentConversionContext<T> conversionContext) {
         List<String> values = nettyHeaders.getAll(name);
diff --git a/http-netty/src/main/java/io/micronaut/http/netty/body/NettyCharSequenceBodyWriter.java b/http-netty/src/main/java/io/micronaut/http/netty/body/NettyCharSequenceBodyWriter.java
index f52c55d6ae4..667612991cb 100644
--- a/http-netty/src/main/java/io/micronaut/http/netty/body/NettyCharSequenceBodyWriter.java
+++ b/http-netty/src/main/java/io/micronaut/http/netty/body/NettyCharSequenceBodyWriter.java
@@ -22,7 +22,6 @@
 import io.micronaut.core.type.MutableHeaders;
 import io.micronaut.http.ByteBodyHttpResponse;
 import io.micronaut.http.ByteBodyHttpResponseWrapper;
-import io.micronaut.http.HttpHeaders;
 import io.micronaut.http.HttpRequest;
 import io.micronaut.http.MediaType;
 import io.micronaut.http.MutableHttpHeaders;
@@ -63,7 +62,7 @@ public ByteBodyHttpResponse<?> write(ByteBufferFactory<?, ?> bufferFactory, Http
             ByteBufUtil.writeUtf8(ByteBufAllocator.DEFAULT, object) :
             ByteBufUtil.encodeString(ByteBufAllocator.DEFAULT, CharBuffer.wrap(object), charset);
         NettyHttpHeaders nettyHttpHeaders = (NettyHttpHeaders) headers;
-        if (!nettyHttpHeaders.contains(HttpHeaders.CONTENT_TYPE)) {
+        if (!nettyHttpHeaders.contains(HttpHeaderNames.CONTENT_TYPE)) {
             nettyHttpHeaders.set(HttpHeaderNames.CONTENT_TYPE, mediaType);
         }
         return ByteBodyHttpResponseWrapper.wrap(outgoingResponse, new AvailableNettyByteBody(byteBuf));
diff --git a/http-netty/src/main/java/io/micronaut/http/netty/body/NettyWritableBodyWriter.java b/http-netty/src/main/java/io/micronaut/http/netty/body/NettyWritableBodyWriter.java
index 63ac58fd5e5..0a31a039fc1 100644
--- a/http-netty/src/main/java/io/micronaut/http/netty/body/NettyWritableBodyWriter.java
+++ b/http-netty/src/main/java/io/micronaut/http/netty/body/NettyWritableBodyWriter.java
@@ -26,7 +26,6 @@
 import io.micronaut.core.type.MutableHeaders;
 import io.micronaut.http.ByteBodyHttpResponse;
 import io.micronaut.http.ByteBodyHttpResponseWrapper;
-import io.micronaut.http.HttpHeaders;
 import io.micronaut.http.HttpRequest;
 import io.micronaut.http.MediaType;
 import io.micronaut.http.MutableHttpHeaders;
@@ -41,6 +40,7 @@
 import io.micronaut.runtime.ApplicationConfiguration;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.ByteBufOutputStream;
+import io.netty.handler.codec.http.HttpHeaderNames;
 import jakarta.inject.Singleton;
 import org.reactivestreams.Publisher;
 
@@ -76,7 +76,7 @@ public boolean isBlocking() {
     @Override
     public ByteBodyHttpResponse<?> write(ByteBufferFactory<?, ?> bufferFactory, HttpRequest<?> request, MutableHttpResponse<Writable> outgoingResponse, Argument<Writable> type, MediaType mediaType, Writable object) throws CodecException {
         MutableHttpHeaders outgoingHeaders = outgoingResponse.getHeaders();
-        if (mediaType != null && !outgoingHeaders.contains(HttpHeaders.CONTENT_TYPE)) {
+        if (mediaType != null && !outgoingHeaders.contains(HttpHeaderNames.CONTENT_TYPE)) {
             outgoingHeaders.contentType(mediaType);
         }
         ByteBufOutputStream outputStream = new ByteBufOutputStream(ByteBufAllocator.DEFAULT.buffer());
diff --git a/http-server-netty/src/main/java/io/micronaut/http/server/netty/body/AbstractFileBodyWriter.java b/http-server-netty/src/main/java/io/micronaut/http/server/netty/body/AbstractFileBodyWriter.java
index 389e5d23985..23de9f08de3 100644
--- a/http-server-netty/src/main/java/io/micronaut/http/server/netty/body/AbstractFileBodyWriter.java
+++ b/http-server-netty/src/main/java/io/micronaut/http/server/netty/body/AbstractFileBodyWriter.java
@@ -27,6 +27,7 @@
 import io.micronaut.http.netty.body.AvailableNettyByteBody;
 import io.micronaut.http.server.netty.configuration.NettyHttpServerConfiguration;
 import io.micronaut.http.server.types.files.FileCustomizableResponseType;
+import io.netty.handler.codec.http.HttpHeaderNames;
 
 import java.time.LocalDateTime;
 import java.time.ZonedDateTime;
@@ -70,8 +71,8 @@ protected boolean handleIfModifiedAndHeaders(HttpRequest<?> request, MutableHttp
             }
         }
 
-        if (!response.getHeaders().contains(HttpHeaders.CONTENT_TYPE)) {
-            response.header(HttpHeaders.CONTENT_TYPE, systemFile.getMediaType().toString());
+        if (!response.getHeaders().contains(HttpHeaderNames.CONTENT_TYPE)) {
+            response.header(HttpHeaderNames.CONTENT_TYPE, systemFile.getMediaType().toString());
         }
         setDateAndCacheHeaders(response, lastModified);
         systemFile.process(nettyResponse);
@@ -86,7 +87,7 @@ protected void setDateAndCacheHeaders(MutableHttpResponse response, long lastMod
         // Date header
         MutableHttpHeaders headers = response.getHeaders();
         LocalDateTime now = LocalDateTime.now();
-        if (!headers.contains(HttpHeaders.DATE)) {
+        if (!headers.contains(HttpHeaderNames.DATE)) {
             headers.date(now);
         }
 
diff --git a/http/src/main/java/io/micronaut/http/HttpHeaders.java b/http/src/main/java/io/micronaut/http/HttpHeaders.java
index 7aeba92751c..26e43217ffa 100644
--- a/http/src/main/java/io/micronaut/http/HttpHeaders.java
+++ b/http/src/main/java/io/micronaut/http/HttpHeaders.java
@@ -622,6 +622,17 @@ public interface HttpHeaders extends Headers {
         X_AUTH_TOKEN
     ));
 
+    /**
+     * Whether the given key is contained within these values.
+     *
+     * @param name The key name
+     * @return True if it is
+     * @since 4.8.0
+     */
+    default boolean contains(CharSequence name) {
+        return contains(name.toString());
+    }
+
     /**
      * Obtain the date header.
      *