Yeah, but that's just the scientific process of hypothesis -> evidence -> conclusion.

You need a measurement that can falsify hypotheses and reject branches that won't work.

Also, if all you have left in your project are performance issues that are hard to identify without flailing around (even with Fable/Astra) despite sampler/profiler reports, then you're doing really well and I wouldn't assume you're going to fare much better than the sota models in terms of stabs in the dark.