Here are some example scenarios to demonstrate how knowing or not knowing the answers to these questions can help or hurt your project.
Client requires fast load times on a global site
If they had not identified that the site needed a CDN, they might have stored the assets in ways that don't support CDNs out of the box. Additionally, they knew to configure the system to be aware of the CDN, so that the links are added properly. This avoided a costly delay in the project's go-live as they would have needed to re-link assets on the site. This resulted in a site that loaded quickly from day one.
Performance issue due to on-premise hosting limitations
The front-end developers did not pay close attention to optimization of resources like JS, CSS stylesheets and images. This led to a home page that loaded approximately 5MB of data spread across approximately 150 requests for new visitors and visitors with expired client caches. The organization hosted the site on-premise along with other mission critical services not connected to the web site. The organization had relatively limited bandwidth and the added request load from the un-optimized home page resulted in an outage not only for the website, but for the other mission critical services.
If they considered the production environment's limitations, they could have avoided this issue by focusing more on the web site performance and considering to host this web site elsewhere. This would prevent the chain reaction from bringing down the unrelated services.
Handling traffic spikes
When discussing the traffic requirements for a project, a partner found that regular daily traffic is generally moderate to low, but the client expects significantly higher traffic once a quarter, due to a regular event. The partner used this knowledge to pitch Azure autoscaling features to keep costs lower while still providing capacity to handle these quarterly spikes. The client appreciated the partner's considerations of budget while maintaining performance year-round.