I think some of the misunderstanding in these comments comes from not fully appreciating the perspective of not-for-profit organisations. While I can't speak for Khan Academy, I know that in every NFP organisation I have worked for there is an acute awareness that funding could dry up one day and the prime directive is to ensure that in a scenario like that, the work of the organisation can continue.
In this case, it leads to a higher concern about minimising the cost of the operational services than you might have in a for-profit organisation. In all the strategic planning I have been involved in with NFP, we always have the "what if worst case scenario arises" plan and in that plan the ability to scale down to bare minimum operational cost is key. It may not be conscious but I suspect that may be part of the reason the performance savings from moving to Go are so attractive in this case, where most profit-making companies just ask the question of whether they can afford to pay for the servers with their current margin or not and if they can they have more important things to worry about.
In this case, it leads to a higher concern about minimising the cost of the operational services than you might have in a for-profit organisation. In all the strategic planning I have been involved in with NFP, we always have the "what if worst case scenario arises" plan and in that plan the ability to scale down to bare minimum operational cost is key. It may not be conscious but I suspect that may be part of the reason the performance savings from moving to Go are so attractive in this case, where most profit-making companies just ask the question of whether they can afford to pay for the servers with their current margin or not and if they can they have more important things to worry about.