I was getting the delay with both Mithril and Adamant bars. I understand mistakes and making the bot not tick perfect is a good thing for anti-ban, but it was basically like clockwork that it would stall for the same 5-10 seconds every time between depositing the bars and withdrawing more coal. If it needed to use a stamina potion, it would run as normal without the delay, but otherwise it would stall at the same point consistently.
Like I said, I understand it's not feasible or even a good thing for the bot to be tick-perfect but only running at 66% can really cut into profits, especially since it costs gold to use the Blast Furnace.