SEOPress vs Slim SEO: settings you control against defaults you don't
Slim SEO is lighter and prints structured data that SEOPress free does not: +10.0 ms and 10 schema types against +24.5 ms and none. SEOPress gives you a real settings interface, more X tags and a paid tier; Slim SEO gives you almost nothing to configure.
Neither plugin was configured before measuring: our benchmark tests the free SEOPress and Slim SEO downloads at their shipped defaults, on WordPress 7.1 with PHP 8.2. Hydrogen SEO, the plugin we build, sits outside this pair.
The numbers
| Measured | SEOPress 10.2 | Slim SEO 4.10.1 |
|---|---|---|
| Front-end PHP time added | +24.5 ms | +10 ms |
| Peak memory added | +6.5 MB | +2 MB |
| Database queries added | +1 | +2 |
| Hooks registered | +114 | +51 |
<head> bytes added | +2,380 | +1,649 |
| Meta description by default | Yes | Yes |
| JSON-LD types printed | 0 | 10 |
| Open Graph / X tags | 10 / 6 | 11 / 2 |
| Sitemap URLs listed | 58 | 73 |
| Sitemap image entries | 40 | 40 |
lastmod coverage | 50 / 58 | 50 / 73 |
| Custom database tables | 1 | 0 |
| Autoloaded options added | +3.6 KB | -0.2 KB |
| Plugin package size | 11.7 MB | 1.4 MB |
| Block editor assets | 17 files, 217 KB | 14 files, 187.7 KB |
| After deactivation | No reduction at all | Releases everything |
Measured on one WordPress 7.1 install (PHP 8.2, MySQL 8.0, Twenty Twenty-Five, 40 posts), each plugin alone with default settings, against a no-plugin baseline. Bold marks the better number in each row. Full method: how we tested.
What the numbers mean
Slim SEO wins most cost rows. It used +2.0 MB of memory against SEOPress's +6.5 MB, registered 51 hooks against 114, grew <head> by 1,649 bytes against 2,380, and ships 1.4 MB against 11.7 MB. It creates no tables; SEOPress creates one. SEOPress wins on queries (1 against 2), which is a small difference either way. In the editor, both are light: 187.7 KB for Slim SEO, 217 KB for SEOPress.
Slim SEO's smaller head is notable because it carries more: a 3,828-byte graph with 10 JSON-LD types, where SEOPress free printed no structured data at defaults. SEOPress's head is smaller than most plugins only because it leaves schema out.
The sitemaps are closer than any other row. Both include archives and all 40 featured images. Slim SEO listed 73 URLs and left 23 without lastmod; SEOPress listed 58 and left 8 without. Neither stamps every URL, so if accurate lastmod matters to you, neither is the strongest choice here. SEOPress uses the unusual /sitemaps.xml path; Slim SEO uses /sitemap.xml.
Social output favors SEOPress on X and Slim SEO on Open Graph: 10 Open Graph and 6 X tags for SEOPress, 11 and 2 for Slim SEO. Both generate meta descriptions.
The admin is where they really differ. Slim SEO added no admin menu items at all; SEOPress adds two and a full settings interface, with a dashboard that measured 185.5 KB. On deactivation Slim SEO released everything, while SEOPress released none of its autoloaded options. If you want to configure things, SEOPress lets you; if you want to never open a settings page, Slim SEO is built for that.
Choose SEOPress if
- You want a settings interface and a paid tier with more features.
- You want fuller X card output (6 tags against 2).
- You manage client sites and want visible, configurable SEO screens.
- You are fine buying SEOPress PRO or adding a separate schema plugin, since the free version printed none.
Choose Slim SEO if
- You want schema from the free plugin (10 types at defaults).
- You want a smaller footprint: 1.4 MB, no tables, +1,649 head bytes.
- You never want to open an SEO settings screen.
- You want a clean deactivation.
Switching between them
Both plugins include migration tools for importing from other SEO plugins; check each one's documentation to confirm the other is a supported source. Since Slim SEO has few settings, moving to it mostly means carrying per-post titles, descriptions and redirects. Moving to SEOPress means configuring its settings afterwards. Hydrogen SEO's importer recognizes SEOPress and Slim SEO alike, and per-page redirects from SEOPress come along; the migration doc has the field list.
Common questions
Is Slim SEO lighter than SEOPress?
On most measures: +10.0 ms and +2.0 MB against +24.5 ms and +6.5 MB, with a 1.4 MB package against 11.7 MB. SEOPress added one fewer query.
Does either print schema for free?
Slim SEO printed 10 JSON-LD types at defaults. SEOPress free printed none on a standard post.
Do both include images in the sitemap?
Yes, both included all 40 featured images. Both also left some URLs without lastmod: 23 of 73 for Slim SEO, 8 of 58 for SEOPress.