Q&A: Child theme bloat and when to build a new theme

I got these questions from a viewer earlier today. They are fairly common so here are the questions and my answers. Keep in mind that everyone who works with WordPress or on the web in general has strong preferences one way or the other, so if you disagree with anything I say, leave it in the comments and let’s discuss!

Now for the questions:

I wondered if I could trouble you to ask just two broad/philosophical questions regarding child-themes? These are pretty “general interest” questions….

  1. If it includes a lot of CSS/template files, does a child theme eventually slow down the loading of a site? It seems that it would, since the child theme is overriding the parent theme, not replacing it. Is this true?
  2. At what point should I be taking a theme (like twentyten or other) as a starting point and build my own theme, rather than building a child theme? It seems that, at some point, if one overrides much of the original theme, there seems to be less benefit gained from parent theme updates etc. and an increased risk of having a really bulky site. (Though I’m not sure I’m experienced enough to build a complete theme quite yet without missing something important – like security etc.)

I’d be really interested to hear your thoughts, if you have a couple of minutes to share them.

Thanks, Jodi

Child Theme Bloat

A child theme doesn’t really bog down the site any more than a regular theme, even if it is completely rewriting all of the parent theme. Let me break it down for you:

If you use @import or another method to load the original stylesheet, then you are loading two stylesheets, but WordPress stylesheets are relatively small and uncomplicated so it’s not that much of a tax on the server. If you roll your own styles entirely, you are just loading one stylesheet.

The parent theme functions.php file will always load along side your child theme functions.php file, but again these files are relatively small so the tax is negligible.

If you make any other template files in your child theme (header.php, index.php, new_cusom_file.php) these will be loaded in place of or in addition to the parent theme files. In other words you’ll never load both the parent theme and the child theme template file and then only display the contents of one of them.

Themes from scratch

As for when you want to build a theme from scratch, that’s a bit more complicated to answer. I build all my themes from scratch because I want full control over everything. I always work from custom designs created to match client or project criteria and rarely start off with something that can be easily built from an existing theme. I’m also obsessed with clean code, standards, and modern approaches so building from scratch every time allows me total control and room to always stay on the bleeding edge of what is being done.

If you design a site from scratch and want it to do specific things, building a theme from the bottom up is often a better idea. But, if you find a theme that already has the majority of what you need, customizing it with a child theme is a lot quicker and easier and will make upkeep easier to handle.

If you want to build your own theme from scratch there are many places you can start. I personally like to start with as little interference as possible so I use a highly personalized version of the _s (“Underscores”) theme. _s is about as stripped down as you can get and to use it you have to do a lot of work, but you also have complete control.

If that’s too stripped down for your tastes there are other great themes to start with including Toolbox. Some developers prefer starting with frameworks like Responsive, WP Fondation, WP Bootstrap, or others, but I think these are colossally overloaded and end up bringing a whole new range of complications.

I have no perfect answer for you on this one. My best suggestion is to master the art of the child theme and then take those skills and apply them to a starter theme like _s.

Hope that helps!

By Morten Rand-Hendriksen

Morten Rand-Hendriksen is a Senior Staff Instructor at LinkedIn Learning (formerly specializing in AI, bleeding edge web technologies, and the intersection between technology and humanity. He also occasionally teaches at Emily Carr University of Art and Design. He is a popular conference and workshop speaker on all things tech ethics, AI, web technologies, and open source.

One reply on “Q&A: Child theme bloat and when to build a new theme”

Hi, Morten,

I recently went back to your Lynda Child Theme course and found lots of the answers to style ideas and configuration — thanks for your very detailed instructions.

We are in the midst of making a new child theme and I have noticed a style that seems new to me: a static banner, in the banner one link for contact, no page drop down menus, and the portfolio, and all contact details on one page. It is an optimised webpage for mobile devices, but different somehow. You can see it on this link here:

I have been fooling around with the stylesheet to get something similar with varying results. Any chance for a blog article on this or a code snippet if time permits?



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