PreloadAllModules could be very CPU and bandwidth intensive for large apps, and thus considered a bad practice. This is an automatically generated app which demonstrates this.
As you can see from the comparison below, using PreloadAllModules is ~15x more CPU expensive compared to not using it.
Keep in mind that this example does not represent the average Angular app because it contains 500 generated routes. For an app with a few dozens of lazy routes the impact will be significantly lower.
MIT