Common bad practices I see all the time:
1 Cheap/low-resource hosting
2 Outdated PHP version
3 Using heavy ThemeForest themes
4 Using heavy page builders like WPBakery, Divi, Avada Builder, etc.
5 Sliders, animations or videos above the fold (ATF)
6 Using Jetpack with too many features enabled
7 Multiple optimization plugins doing the same thing (minification, cache…) → conflicts
8 Installing plugins “just in case”
9 Plugins and themes not updated
10 Uploading images “as they are”, instead of resizing them to the exact display size
11 Very large or uncleaned database (especially WooCommerce sites)
12 Using iframes or external scripts that load resources from third-party servers
