Not dev, but a perf-eng confidence boost.

Our company was hired by a client to onboard perf-testing process and do some perf-related go-live stuff. Basically, make sure the app meets the SLAs.

Our company mobilized some internal resources for the task. The had 3-4 months. 2 months later they realized they won't pull it off. What a shame...

When the threat of dropping the ball and losing the client and recommendations became very real, they engaged us. Half the time, half the resources, a worried and annoyed client who now wants to control the whole initiative.

During the first 2 meetings we get the general idea of what they have, what they want. We take some time to prepare a plan to make it on time. The client argues our plan, mostly because one of the main points was mocking downstream dependencies [integrations]. He asks, then demands to do it all with live integrations. We explain why this is an incredible risk and why we should do it the proposed way. He disagrees.

Alright then... Maybe he knows smth we don't. Let's do it the risky way...

A month later test results are far from the target. I did my best with app de-bottlenecking and fine-tuning. But since the live integrations do not deliver, they hide other bottlenecks. The initiative is stuck.

Finally, the client agrees to do it with mocking. But now there's no time left as it will take almost a month to prepare mocks...

The client agrees we should have done it our way from the start. They postpone the go-live and we carry out our testing and tuning the right way.

That was one expensive and long "I told you so". But it boosted our [perf team's] confidence to the top and beyond :)

don't tell us how to do our job, unless you do want extra expenses