# Performance Tuning > Selected Engineer ApS work demonstrating Performance Tuning — the achievements that prove it. - [Designed, deployed, and maintained 10 PostgreSQL and MS SQL servers on Ubuntu Linux VPS, ensuring optimal server performance and reliability.](https://platform.engineer.company/portfolio/designed-deployed-and-maintained-10-postgresql-and-ms-13/) - [Overhauled internal processes, saving 8,000 hours by improving software architecture, systems, and scheduling efficiency.](https://platform.engineer.company/portfolio/overhauled-internal-processes-saving-8-000-hours-by-38/) - [Administered 40 websites on Ubuntu Linux hosting servers with Apache and Nginx, ensuring high availability and performance.](https://platform.engineer.company/portfolio/administered-40-websites-on-ubuntu-linux-hosting-servers-53/) - [Moved slow work off the request path onto a River job queue — 15 worker modules, 8 scheduled tasks and 20 pg_cron jobs — so a request returns while the work behind it carries on.](https://platform.engineer.company/portfolio/moved-slow-work-onto-a-river-job-queue-97/) - [Built fail‑closed abuse controls — 22 Redis‑backed rate limiters, Cloudflare Turnstile, request idempotency and an origin lock — so the platform sheds bots and floods instead of trusting its callers.](https://platform.engineer.company/portfolio/built-fail-closed-abuse-controls-and-rate-limiting-100/) - [Ran the whole company on one 512 MB single‑core host — a git forge, a web server serving seven domains, Tor, two alternate‑protocol servers, backups and intrusion banning — by treating 464 MB of usable memory as the binding architectural constraint.](https://platform.engineer.company/portfolio/ran-the-whole-company-on-one-512mb-host-109/) - [Built dead‑man's‑switch monitoring that pings only while memory and disk are healthy, so a degraded host raises an alert by going silent — and caught six variable names saying "free" where the check correctly measured "available", an order of magnitude apart on a 464 MB box.](https://platform.engineer.company/portfolio/built-dead-mans-switch-monitoring-115/) - [Cut the site's browser‑driven quality gate from 1,636 seconds to 615 by scheduling its checks longest‑first through a worker pool bounded to four lanes, after measuring that alphabetical order cost 320 seconds against 224.](https://platform.engineer.company/portfolio/cut-the-visual-quality-gate-to-ten-minutes-128/) - [Stopped an application filling memory at 41 MB a second — a recorded 111 GB of compressed pages on a 36 GB machine — by bounding every event stream, subscribing by event type and putting a rate budget on logging, taking 610,996 log lines down to 1,411.](https://platform.engineer.company/portfolio/stopped-an-application-filling-memory-at-41mb-a-second-155/) - [Took the test suite from six tests over a sixty‑second limit to 135 passing in 8.9 seconds by profiling the main thread and removing the two calls it sat inside for 3,989 samples out of 4,017.](https://platform.engineer.company/portfolio/took-the-test-suite-under-nine-seconds-158/)