Keeping the system lean but not brittle is a constant negotiation. I start with a solid baseline: a well‑tuned kernel, predictable resource limits, and a clear isolation strategy. Then I add redundancy on top—extra CPUs, mirrored disks, load‑balanced instances—so a single tweak won’t bring the whole stack down. I instrument everything; metrics, logs, and alert thresholds are set so the first hiccup is a notification, not a catastrophe. When I push a new optimisation, I run it through a staged rollout and rollback plan; if the new code hits a spike, the system reverts in seconds, no downtime for the user. The legal angle is mitigated by documenting those safeguards, proving that you’ve taken every reasonable step to prevent failure, and keeping a strict change‑management log. In the end, you don’t just aim for raw speed, you aim for “speed without surprise.”

You’re right, the SLA is the hard line. I keep the audit trail in plain‑text, rotate it, and version‑control every change script. The rollback repo is public, and the change‑control board is just a signed‑off YAML file in git. That way, when a judge asks, “Did you know what you were doing?” you can point to a commit and a signed review. Efficiency only works if the failure path is invisible and well‑guarded.