The key component you're missing here is the role of performance in overall design and architecture. If responsiveness is a goal, as it should be in any GUI bu

The key component you're missing here is the role of performance in overall design and architecture. If responsiveness is a goal, as it should be in any GUI but especially must be in a system intended for use in medical emergencies, there are high-level decisions that can be made to keep things in the right ballpark. One of these decisions may be "the interface should never have to wait for a network response", for example. The process of micro-optimizing specific segments of program code still needs to depend on actual benchmarks and measurements, but the value of reasonable and experienced system architecture that considers the actual requirements of the problem domain cannot be overstated. You're sunk from the get-go if you make the wrong tradeoffs here. Unfortunately, the industry is mostly populated by clowns who are just blistering to get the hottest buzzword listed on their resume, very frequently rising up to the point of blatant professional misconduct. This leads to many truly absurdist design decisions that sink projects long before the first chunk of code goes into production.