Your site is slow, or it keeps hitting its PHP worker limit, and you have no idea which plugin is responsible. Most tools are either developer debug bars too heavy to leave on, expensive services that do not run on shared hosting, or lab benchmarks of a plugin on a clean site rather than your site.
Pagemeter is a simple, on-demand speed test for your own site. Click Run test and it loads your front page a few times, both cached (what real visitors get) and uncached (a genuine cache miss), then shows you one screen with:
Every test is saved, so each time you optimize, remove, or reconfigure a plugin you can watch the numbers drop and prove the improvement.
Nothing is recorded except during a test you start yourself, so there is zero measurement overhead on normal visitor traffic.
It also includes an optional domain governor: a blocklist you configure to stop a dead or unwanted endpoint from slowing your site. Nothing is blocked by default.
Pagemeter measures locally and stores everything in your own database. It does not contact any external server and contains no telemetry. No data about your site or your plugins leaves your site.