Improve nginx performance.

Signed-off-by: Gontier Julien <gontierjulien68@gmail.com>

preset/nginx.conf

@@ -22,6 +22,12 @@ events {
 }
 
 http {
+	# By default, multi-threading is disabled, so we enable it.
+	aio threads;
+
+	# Even if it not really need, it always good practice to set it up.
+    charset utf-8;
+
 	# Includes mapping of file name extensions to MIME types of responses
 	# and defines the default type.
 	include /etc/nginx/mime.types;