The toughest part of the circuit goes from Thorong Phedi to Thorong La pass (5,416m). There exists a steep 45 moment climb at this altitude, which is able to go ahead and take breath away from you. The views are worth it although! That looks like an amazing journey you https://www.discoveryworldtrekking.com/annapurna-circuit-trek-with-tilicho-lake.html