The biggest lesson I learned : don't upgrade before checking resource usage
I used to assume a slow website meant I needed a bigger server.
Now the first things I check are CPU usage, RAM, disk I/O load average and database performance. Most of the time the issue isn't the hosting plan, it's application, plugins or query that's using more resources than it should.
That simple habit has saved me several unnecessary upgrades and made troubleshooting much easier.
Has anyone else had similar experience?