10× more WordPress sites per server.
A WordPress site carries a PHP-FPM pool, a database server and an object cache. A BookPress site is one native process and one embedded database. Under sustained load it holds a site in about 170 MB where a tuned WordPress stack needs about 1.7 GB, so a box sized by memory fits about ten times as many. The memory numbers, and the honest fresh-box figure →
Same memory budget, ten times the sites. Memory in use under sustained load, plugins active, measured 26 September 2026.
Density is a memory question, so we measured memory.
A host sizes a box by the resource that runs out first, and for WordPress that is memory: PHP-FPM starts its workers up front and each one holds its own memory, whether or not requests arrive. BookPress carries no pool. We count memory the fair way for WordPress: memory the PHP workers share (the OPcache) is counted once, not once per worker.
| What is being measured | BookPress | WordPress stack | Lighter by |
|---|---|---|---|
| Live plugin site, under sustained load | ~170 MB | ~1.7 GB | ~10× |
| Same site, tuned 64-worker pool, freshly booted | ~170 MB | ~449 MB | ~2.6× |
| Same site, right-sized 8-worker stack | ~170 MB | ~369 MB | ~2.2× |
| Site with no plugins | 16.5 MB | 1.07 GB | ~65× |
Google Cloud 4-vCPU machines (c2-standard-4 Intel, c4a-standard-4 ARM), WordPress tuned with PHP-FPM, OPcache and JIT, a Redis object cache and MariaDB. We measured the site with no plugins on Twenty Twenty-Five with WordPress's own sample content.
The 10× is the under-load figure, and that condition travels with it. A good part of the memory a WordPress stack holds under load is configured limits rather than live demand, a 64-child pool sized for peak, so a smaller box runs a smaller configuration. Freshly booted, the same tuned stack is about 2.6× heavier than BookPress; right-sized to eight workers, about 2.2×. We lead with the under-load number because that is the box a host actually provisions, and we would rather show the other two than let the headline stand alone.
A mostly-idle site costs about 198 kB.
Most sites on a shared platform are quiet most of the time. On a PHP stack a quiet site still holds a pool of processes waiting for a request that may not come. On BookPress it holds almost nothing: we measured the marginal cost of one more idle site rather than estimating it, and it is about 198 kB of memory. Thousands of low-traffic sites fit on one modest server, and an idle site's cost approaches the cost of its storage.
✓ No worker pool
One process serves many sites, the way nginx does. There is no per-site pool of PHP workers held in memory against a burst that may never arrive.
✓ No database server
Storage is embedded SQLite on the same WordPress schema, in-process. An idle site holds no database connection and no server kept running on its behalf.
✓ No cache tiers
No object cache and no page cache to keep warm per site. Rendering from scratch is the fast path, so there is no stored copy to hold in memory.
✓ One binary, shared
The 1.8 MB program and each theme are loaded once and shared by every site on the box, so a thousand sites on one theme cost one copy of it.
Fewer machines for the same fleet.
Density is a bill. A box that held tens of PHP workers holds
thousands of BookPress sites, so the same book of clients runs on a fraction of the
hardware, and the sites keep their themes, their /wp-admin and their
URLs while doing it.
If you run the servers
BookPress is software you run on your own infrastructure, licensed by the site up to 500 and by the vCPU above that. A site arrives as a standard MySQL dump and can leave the same way.
If a host runs them for you
You do not install BookPress yourself; you ask the host who runs your sites whether they will. The density is what makes that an easy conversation: it lowers their bill for the same fleet.
What it costs
Priced against the infrastructure you stop renting: per site from €1 down to €0.45, and per licensed vCPU past 500 sites. Billed annually.
Size it against your own fleet
Tell us how many sites you run, which plugins are on them, and where you host them today, and we will work the density and the saving against your own numbers.
hello@bookpress.io