Serial Programming question

Using Arduino Programming Questions
16

Now I am trying to read 4bytes of data coming from the ATMega32.
1-sync,2-t,3-h,4-f
I inserted that while loop after every Serial1.read()

   if(Serial1.available()>0)
  {
    sync=Serial1.read();
    //delay(500);
    
    if(sync==0xAA)
    {
      Serial.print("Sensor reading \n");
      while(!Serial1.available())
      digitalWrite(13,HIGH);
      //if(Serial1.read()==B00011010) //Address 1=B00011010
      //{
        while(!Serial1.available());
        temp=Serial1.read();
        while(!Serial1.available());
        hu=Serial1.read();
        while(!Serial1.available());
        fcs=Serial1.read();
        digitalWrite(13,LOW);
        if((temp+hu)==fcs)
        {
          Serial.print("Temperature 1 \t");
          Serial.print(temp);
          Serial.print("Humidity 1 \t\n");
          Serial.print(hu);
        }
        else
        Serial.print("Sensor1 Error\n");
      //}
     }
   }

It is very slow(not main problem as the sensor updates the data once every second, but still the data received is lot slower and jitter is also high ) and the error rate is too high. Is there any programming improvement to reduce the errors and jitter(speed is secondary)