Chinese Web Fonts Are Why Your Site Loads Slowly

1. Why CJK fonts are so much heavier

The gap is a matter of how the writing systems work. A Latin font weight covers an alphabet, digits, punctuation and accented forms, which comes to roughly 200 to 400 glyphs, around 20 to 40 KB once compressed to woff2. Chinese has no alphabet: every word is written with characters that each need their own drawn glyph, and everyday use already runs to five or six thousand of them, with a full set past twenty thousand. Japanese adds two kana syllabaries on top of several thousand kanji, and Korean fonts normally ship over eleven thousand precomposed hangul syllables. Compressed the same way, one CJK weight lands somewhere between 3 and 8 MB. That is a hundredfold difference, not a slight increase.

The weight then stacks up further. Variable fonts pack several weights into one file, which is convenient and also bigger. Sites in Chinese also tend to use one family for headings and another for body text, so two large files load at once. Put two CJK families on a site and the fonts alone can outweigh everything else you serve.

Fonts differ from images in one way that matters. An image that has not finished loading does not stop the text beside it from being read. A font that has not finished loading leaves its text either missing or drawn in a system face that swaps out later. Those are the blank seconds the visitor sits through, and measurement tools report them directly as poor first contentful paint and largest contentful paint figures.

When Google's font service delivers Chinese it splits the family into hundreds of small slices. That sounds like it spreads the load, but the more varied the characters on your page, the more slices actually get downloaded, and the total does not shrink. Mobile networks and older handsets take the worst of it, while a desktop on a fixed line hides the problem entirely, which is why anyone testing on desktop alone concludes everything is fine.

2. Confirming that fonts are the cause

The quickest route is to put the URL into Google PageSpeed Insights and see whether fonts appear among the items it blames for the load time. For a closer look, press F12 in the browser, open the network tab and reload, then check how large each font file is and how long it took.

The giveaway is timing. If the moment text appears on screen lines up with the moment the last font file finished downloading, you have your culprit. Then look at which element on the page is the largest piece of content. If it is a line of heading text, the case against the fonts gets stronger.

3. Four fixes, easiest first

These four work in order. The first two pay off the same day; the last two take some work. With all four done, a site that was loading several CJK families can realistically get total font weight under 200 KB.

The order is deliberate. The first two remove things you do not need: count how many families the site actually loads, then delete the decorative ones that appear in a block or two. That alone usually solves most of it. The last two are about handling the family you kept properly, and they take more effort. Measure again after each step, so you know which one earned its keep.

Using system fonts for body text means naming the Chinese faces already installed on the reader's device, so the browser downloads nothing. A common stack for Traditional Chinese is -apple-system, PingFang TC, Microsoft JhengHei, Noto Sans TC, with sans-serif at the end as a backstop. For Simplified Chinese the equivalents are PingFang SC, Microsoft YaHei and Noto Sans SC.

4. Keeping only the characters you use, and what it costs

The tooling side holds no mystery. There are ready-made programs that scan which characters the site actually uses, produce a cut-down font file and write it out as woff2, which compresses better. It runs in seconds. If the font has adjustable weight, narrowing the weight range to what you really use brings the size down further.

A line mixing the subset font with the system font reads as slightly wrong without the reader being able to say which character is at fault. Before committing to this step, be sure you can keep the regeneration going. If you cannot, the layout will quietly degrade over a few months.

The way to control that risk is to make regeneration automatic. Hook the subsetting into the build process or the publishing process so new content triggers a run before it goes live, and missing characters never accumulate. Take the character list from the compiled page content rather than maintaining a list by hand, which is far more reliable.

If automation is out of reach, at least include a standard list of common characters in the heading font's subset as a buffer, at the cost of a somewhat larger file. Keep the original full font file and the steps used to produce the subset, so whoever takes over can rebuild it. And before each release, look over the headings and the navigation with real article content in place. Missing characters are usually obvious to the eye.

5. What to show during the seconds before the font arrives

font-display decides how the browser treats text while the font is still downloading. With swap, the text is drawn in a system face immediately and replaced when the font arrives, so nothing disappears, at the cost of a layout jump at the moment of the swap. With optional, the browser gives up on the font for that visit if it does not arrive quickly, which keeps the layout completely stable, at the cost of some visitors seeing a system face on their first visit.

For most sites, swap on body text is the right call, because at least no paragraph goes blank. Consider optional only if removing the layout jump matters more than everyone seeing the typeface you chose. If that shift really bothers you, tune the fallback font's metrics with size-adjust and ascent-override so its character widths and line height sit close to the real font, and the movement at swap time becomes hard to notice.

6. What self-hosting fixes on the side

Beyond speed, bringing fonts in-house sorts out two other things. Security settings get simpler: a site can restrict which outside hosts it is allowed to request anything from, and two fewer sources means a shorter list to maintain. And there is privacy: you no longer have to tell visitors their connection details go to Google's font service. After the German court ruling on Google Fonts in 2022, which held that embedding them sent visitors' IP addresses to Google without consent, sites with EU visitors tend to care about that point.

Two things to set up once you have self-hosted. Give the font files a long cache lifetime and put a version number in the filename, so a redesign only needs a new filename and returning visitors do not download anything again. And check the licence first: Noto and the Source Han families use the SIL Open Font License, which permits both self-hosting and subsetting, while commercial fonts need reading contract by contract.

7. If it is not the fonts, what else it could be

If the score is still poor once fonts are handled, look at two more places. First, images: uncompressed JPEGs and photos uploaded straight off a phone are frequently the largest element on the page in their own right. Second, the page code: when too much runs at once, the page can be drawn and still not respond to a tap, which the visitor reads as the site being stuck.

Working through those is usually enough. Most loading problems on CJK sites stop at fonts and images, well before anything as drastic as changing host.