Lower compress level of png sent on websocket.

server.py

@@ -576,7 +576,7 @@ class PromptServer():
         bytesIO = BytesIO()
         header = struct.pack(">I", type_num)
         bytesIO.write(header)
-        image.save(bytesIO, format=image_type, quality=95, compress_level=4)
+        image.save(bytesIO, format=image_type, quality=95, compress_level=1)
         preview_bytes = bytesIO.getvalue()
         await self.send_bytes(BinaryEventTypes.PREVIEW_IMAGE, preview_bytes, sid=sid)