Measurements. Where every number on this site comes from.
Every number on this site comes from a recorded run on our own hosts, between 27 and 30 Sep 2026. If a number is not on this page or on Compatibility, it is not on the site. None of these runs is a load test: each measures one build at a time on a development host.
Through the public API, 28 Sep 2026
The karts CLI on a Mac, through the public API at api.karts.kartikey.fyi, to our dev host running the same stack as the first run below, in the same development mode. Wall is the CLI's own time; server is the host's build time.
| Run | Result | Wall | Server |
|---|---|---|---|
feature/refunds | Tiny Shop branch with a new migration, on a quiet host: ready; restore 16 ms, clone_init 111 ms, migrations 166 ms, ready 723 ms | 2.23 s | 1.08 s |
main | Tiny Shop, template rebuilt for a new image: ready; template 6.3 s | 9.00 s | 7.48 s |
main, day before | Tiny Shop, first build: ready; template 10.5 s | 13.7 s | 12.0 s |
feature/cleanup | drops customers.notes: refused; no environment left behind | 2.00 s | — |
| split-shop | a web and an API service in one environment: both answer; the web page renders the API's products | 10.17 s | 8.07 s |
| shop-front | a frontend project linked to Tiny Shop: its server-side call reached the backend over the private link | 6.20 s | 4.55 s |
| POST after idle | 5 POSTs to the API, each after 7 s idle: 5/5 answered 200 | — | — |
| host restart | with 4 environments serving: every URL answered 200 again without a new karts up, the link included; the edge answered 502 for about 4.4 s during the restart | — | — |
Miniflux main | a Go app, first build: ready; template 46.4 s, go build 44.8 s | 94.23 s | 91.64 s |
| Miniflux branch | adds a Go migration: ready, migration applied; go build 45.2 s with a cold build cache | 48.68 s | 45.72 s |
| project delete | karts project delete: deleted, and the project's place reused | 3.89-6.15 s | — |
A first karts up of Tiny Shop, template included, took 9.00 s and 13.7 s in these two runs. Apps with larger installs take much longer: see Compatibility.
The first end-to-end karts up, 27 Sep 2026
The karts CLI on a Mac, the control API, the host daemon, a Firecracker micro-VM with its own Postgres, and a public URL with a Let's Encrypt certificate issued on demand. The app is Tiny Shop, our sample Node and Postgres app. The CLI reached the control API over our own private network, not the public API.
Mode. In every run on this page the host daemon ran as an ordinary user: user namespaces, no jailer, no per-VM firewall rules. Everything else was the production code path. The runs are to be repeated under the jailer. See Security.
| Run | Result | CLI wall time | Server build |
|---|---|---|---|
main, first ever | Built the template (10 migrations, seed of 40 customers and 160 orders), ready at main-1add.karts.kartikey.fyi | 29.7 s | 27.8 s (template 26.4 s) |
feature/refunds | Adds 0011_create_refunds.sql; ready at feature-refunds-fc00.karts.kartikey.fyi | 2.3 s | 1.26 s |
feature/discounts | Also adds a 0011; refused: "migration 0011 is already taken by branch feature/refunds; renumber to 0012 or later" | < 1 s | none |
feature/cleanup | 0012 drops customers.notes; refused: "destructive migration refused … ALTER TABLE customers DROP COLUMN notes — drops column customers.notes and every value in it" | < 1 s | none |
Server steps of the feature/refunds build, as karts up --timings prints them. Install took 0 ms because the dependencies came from the cache.
disks 1 ms
restore 16 ms
clone_init 112 ms
files 8 ms
install 0 ms
migrations 230 ms
ready 881 ms
The first request to a new URL took 5.5 s, including issuing its certificate. Later requests took ~0.5 s.
Snapshot restore on the host
Firecracker v1.17.0 on our KVM host, an Intel Core i5-10300H with an NVMe disk, before any of Karts ran on it. A guest was booted once and snapshotted; then new VMs were restored from that snapshot, one after another.
| Measure | Result |
|---|---|
| Snapshot restore to a running guest | 10.7 ms median, 13.2 ms p95, over 100 runs |
| Private host memory per restored VM | about 19 MiB |
| Copy-on-write copy of a 1 GiB disk | 1.4 ms median |
| Cold boot to guest userspace | 1,067 ms median; 312 ms with two kernel arguments and quiet |
| Kernel random generator reseeded after restore | in all 110 clones |
Restore alone excludes the jailer, networking, vsock, clone initialisation and the app. The end-to-end run above includes them, apart from the jailer and the per-VM firewall rules.
