Obviously they are extremely fast in comparison to the best human programmers, but they are still too slow to be our one-to-one enhanced pair programmer. Our current solution is multi-instances, toggling between tasks. However, Multitasking is known to be a poor method, with low productivity and causing harm as it increases cognitive load, stress and fatigue levels.
I am sure that this is temporary and we will soon have coding assistants fast enough for deep focus on single tasks. What do you think?
I wouldn't say "never multitask" but I think you should think carefully about a portfolio of things you can work on that don't conflict with each other.
One possibility to to race analysis of situations with an LLM. For instance punch in a prompt asking if it can figure out the cause of a bug and go off and try figuring it out yourself in the debugger. Or read or write documentation when it is off on a mission.
(I've definitely seen 20 developer teams that were spinning their wheels because they were stomping on each other despite using version control as well as teams that had code rot because they had a "no refactoring/don't touch a file you can possible avoid touching" policy)