Replace the 1ms delay for 2 nops to get a 100ns delay. #259

Marlin/temperature.cpp

   WRITE(MAX6675_SS, 0);
   
   // ensure 100ns delay - a bit extra is fine
-  delay(1);
+  asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
+  asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
   
   // read MSB
   SPDR = 0;