stringbuilder is faster than string but something is still off, most files dont have barely any content

DirectoryScanReceiver/Program.cs

@@ -24,7 +24,7 @@ static class DataExtractor
         if (data.Length == 0) return;
 
         var s = data.Split('|').ToList();
-        if(s.Count < 3) return;
+        if (s.Count < 3) return;
 
         Data.Name = s[0];
 
@@ -42,7 +42,7 @@ static class DataExtractor
 
 static class DataHandler
 {
-    public const string OutputDir = "./output";
+    public const string OutputDir = "output";
 
     public static void Parse(string data)
     {
@@ -54,7 +54,16 @@ static class DataHandler
 
         if (parsed.Name.Length == 0 || parsed.Length == 0 || parsed.Content.Length == 0) return;
 
-        var newPath = Path.Combine(OutputDir, parsed.Name);
+        var processPath = Path.GetDirectoryName(Environment.ProcessPath);
+        if (processPath == null) return;
+
+        var outputDir = Path.Combine(processPath, OutputDir);
+        var newPath = Path.Combine(outputDir, parsed.Name);
+        if (newPath == parsed.Name)
+        {
+            newPath = outputDir + Path.DirectorySeparatorChar + parsed.Name.TrimStart(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
+        } // DO NOT WRITE SOMEWHERE ELSE THAN OUTPUT DIR
+
         var fi = new FileInfo(newPath);
         var dir = Path.GetDirectoryName(newPath) ?? OutputDir;
         var di = new DirectoryInfo(dir);
@@ -94,12 +103,13 @@ internal class Server
         {
             if(!_listener.Pending()) continue;
 
-            var peer = _listener.AcceptTcpClient();
+            using var peer = _listener.AcceptTcpClient();
-            var stream = peer.GetStream();
+            using var stream = peer.GetStream();
 
             Console.WriteLine($"Connected to Peer: {peer.Client.RemoteEndPoint}");
             while (GetState(peer) == TcpState.Established)
             {
+                StringBuilder sb = new();
                 var buffer = "";
 
                 try
@@ -120,14 +130,15 @@ internal class Server
                             var recvCount = stream.Read(recvBytes);
                             if(recvCount <= 0) continue;
 
-                            // TODO: for is to heavy
+                            // TODO: for and string are to heavy
-                            for (var i = 0; i < recvCount; i++) buffer += (char)recvBytes[i];
+                            sb.Append(Encoding.UTF8.GetString(recvBytes));
                             availableBytes -= recvCount;
                         }
                     }
                 }
                 catch (Exception ex) { Console.WriteLine(ex.Message); }
 
+                buffer = sb.ToString();
                 if(buffer.Length == 0) continue;
 
                 foreach (var b in buffer.Split("\r\n\r\n"))