How do you isolate a plugin problem from a server-resource problem?

When a Rust server starts stuttering or behaving unpredictably after changes, how do you normally narrow down whether the problem is a plugin, plugin interaction, server resources, database/storage activity, or something else?
I’m interested in the order people use when troubleshooting, especially on servers with a larger plugin stack.
For example, do you normally start with:
- Recent plugin updates or configuration changes
- Server console errors
- Plugin unload/reload testing
- Resource usage during the issue
- Database or file I/O
- Reproducing it on a test environment
- Temporarily disabling plugins in groups

I know there is no one-size-fits-all answer, but I’d be interested in the practical workflow people trust before they start changing infrastructure or rolling back everything.

Use a profiler and profile the server, Server console errors, Resource usage during the issue, Temporarily disabling plugins in groups