Start here. This is the direct spoken answer to practice first.
Overview
The trade-off becomes manageable only after each dimension is defined for the actual user task.
I first define the minimum acceptable task quality, the latency users can tolerate, and the cost budget per successful outcome. Then I measure candidate models and request designs against the same representative workload. Common levers include using a smaller model, shortening context, limiting output, improving retrieval, caching safe repeated work, streaming the response, or moving non-interactive work to a background workflow. The right point is the cheapest and fastest design that still clears the quality requirement with margin.