I made a simple QGIS plugin that shows the QGIS python variable qgis.utils.plugin_times in an easy to understand window. It will show the QGIS user which of their plugins slows down QGIS startup. If you’re a plugin developer you can compare your plugin’s speed with other plugins, so you can try to optimize your code. The plugin is available on the Official QGIS Plugin Repository as experimental plugin. You can download it from within QGIS if you check the “Show also experimental plugins” option in Plugins | Settings. If you would like to check out the source code, it’s available on Github.