Set process priority to "below normal"

src/LanguageServer/Impl/Program.cs

@@ -28,6 +28,10 @@
 namespace Microsoft.Python.LanguageServer.Server {
     internal static class Program {
         public static void Main(string[] args) {
+#if RELEASE
+            Process.GetCurrentProcess().PriorityClass = ProcessPriorityClass.BelowNormal;
+#endif
+
             CheckDebugMode();
             using (CoreShell.Create()) {
                 var services = CoreShell.Current.ServiceManager;