How fast can you snapshot a running Space?

Checkpointing a running Space that holds 300 MB in RAM and 100 MB on disk took 532.8 ms for a QEMU VM and 274.3 ms for a gVisor container (p50, n = 10 each) on a Mac Studio (Apple M2 Max, 96 GB), measured 2026-10-25. The Space kept running.

Measured 2026-10-25Build app 0.15.0, cua 0.9.0, cua-spacesd 0.8.0Raw data (CSV)

Results

Time for one checkpoint call of a running Space, serial. Lower is better.

QEMU VM
gVisor container

Fastest

429.1 ms

257.9 ms

p50

532.8 ms

274.3 ms

p90

977.7 ms

305.9 ms

p99

1.2 s

310.6 ms

Slowest

1.2 s

310.6 ms

Every result on this page
Result	Value	Fastest	p50	p90	p99	Slowest	n	Measured
QEMU VM	532.8 ms p50	429.1 ms	532.8 ms	977.7 ms	1.2 s	1.2 s	10	2026-10-25
gVisor container	274.3 ms p50	257.9 ms	274.3 ms	305.9 ms	310.6 ms	310.6 ms	10	2026-10-25

Method: QEMU VM

Driver on the host: rollout_bench checkpoint (Rust SDK, built from the tag). The running Space (QEMU Linux VM, 2 vCPU / 2 GiB, --forkable) holds a world of 300 MB random data in /dev/shm and a 100 MB file on disk. Each sample = one Sandboxes.checkpoint(space, name) call of the running Space, start to return (the Space keeps running). n=10, serial, same source; the first QEMU checkpoint was pinned (fork source).

Caveats

The first QEMU checkpoint (pinned, 978 ms) is included.

Environment and build

Machine	Mac Studio, Mac14,13 (Mac Studio)
Chip	Apple M2 Max, 12 cores
Memory	96 GB
OS	macOS 26.6.2 (25G83)
Where	local
Other vms	1
Network	n/a (local)
Kind	vm
Image	ghcr.io/trycua/linux:24.04-slim
Shape	QEMU Linux VM, 2 vCPU / 2 GiB, --forkable, headless
Build	Cua Spaces 0.15.0 DMG (https://github.com/trycua/cua/releases/download/cua-spaces-v0.15.0/cua-spaces-0.15.0-darwin-universal.dmg, sha256 8725a09ba4132aa8a1667fa48c86416c91d5dec0d3c7dc93f88f5f3e29e0aba0): bundled cua 0.9.0, Helpers/cua-spacesd 0.8.0, cua-vz
App	0.15.0
cua	0.9.0
cua_spacesd	0.8.0

Reproduce

# On an Apple silicon Mac (macOS 26), with Rust (rustup) and git:
curl -fLO https://github.com/trycua/cua/releases/download/cua-spaces-v0.15.0/cua-spaces-0.15.0-darwin-universal.dmg
hdiutil attach -nobrowse -mountpoint /tmp/cua-dmg cua-spaces-0.15.0-darwin-universal.dmg
mkdir -p ~/bench && ditto "/tmp/cua-dmg/Cua Spaces.app" ~/bench/"Cua Spaces.app" && hdiutil detach /tmp/cua-dmg
git clone --depth 1 --branch cua-spaces-v0.15.0 https://github.com/trycua/cua ~/bench/cua
(cd ~/bench/cua/libs/cua && cargo build --locked --release -p cua-sdk --example rollout_bench --example channel_bench)
export PATH="$HOME/bench/Cua Spaces.app/Contents/MacOS:$PATH" CUA_HOME=~/bench/home DO_NOT_TRACK=1 CUA_TELEMETRY=0
RB=~/bench/cua/libs/cua/target/release/examples/rollout_bench
cua daemon start --foreground &
$RB create --prefix fsrc- --n 1 --kind vm --cpus 2 --memory-mb 2048 --headless --forkable --keep
cua sb exec fsrc-0 'dd if=/dev/urandom of=/dev/shm/state bs=1M count=300; dd if=/dev/urandom of=$HOME/state.bin bs=1M count=100; sync'
for i in $(seq 1 10); do $RB checkpoint --source fsrc-0 --name ckq-$i; done

Method: gVisor container

Driver on the host: rollout_bench checkpoint (Rust SDK, built from the tag). The running Space (gVisor container, 2 vCPU / 2 GiB) holds a world of 300 MB random data in /dev/shm and a 100 MB file on disk. Each sample = one Sandboxes.checkpoint(space, name) call of the running Space, start to return (the Space keeps running). n=10, serial, same source; the checkpoints were deleted at the end.

Caveats

What a gVisor checkpoint stores follows the runtime's checkpoint support; it wasn't inspected here.

Environment and build

Machine	Mac Studio, Mac14,13 (Mac Studio)
Chip	Apple M2 Max, 12 cores
Memory	96 GB
OS	macOS 26.6.2 (25G83)
Where	local
Other vms	1
Network	n/a (local)
Kind	gvisor
Image	ghcr.io/trycua/linux:24.04-slim
Shape	gVisor container, 2 vCPU / 2 GiB, headless
Build	Cua Spaces 0.15.0 DMG (https://github.com/trycua/cua/releases/download/cua-spaces-v0.15.0/cua-spaces-0.15.0-darwin-universal.dmg, sha256 8725a09ba4132aa8a1667fa48c86416c91d5dec0d3c7dc93f88f5f3e29e0aba0): bundled cua 0.9.0, Helpers/cua-spacesd 0.8.0, cua-vz
App	0.15.0
cua	0.9.0
cua_spacesd	0.8.0

Reproduce

# On an Apple silicon Mac (macOS 26), with Rust (rustup) and git:
curl -fLO https://github.com/trycua/cua/releases/download/cua-spaces-v0.15.0/cua-spaces-0.15.0-darwin-universal.dmg
hdiutil attach -nobrowse -mountpoint /tmp/cua-dmg cua-spaces-0.15.0-darwin-universal.dmg
mkdir -p ~/bench && ditto "/tmp/cua-dmg/Cua Spaces.app" ~/bench/"Cua Spaces.app" && hdiutil detach /tmp/cua-dmg
git clone --depth 1 --branch cua-spaces-v0.15.0 https://github.com/trycua/cua ~/bench/cua
(cd ~/bench/cua/libs/cua && cargo build --locked --release -p cua-sdk --example rollout_bench --example channel_bench)
export PATH="$HOME/bench/Cua Spaces.app/Contents/MacOS:$PATH" CUA_HOME=~/bench/home DO_NOT_TRACK=1 CUA_TELEMETRY=0
RB=~/bench/cua/libs/cua/target/release/examples/rollout_bench
cua daemon start --foreground &
$RB create --prefix fsrc- --n 1 --kind vm --cpus 2 --memory-mb 2048 --headless --forkable --keep
cua sb exec fsrc-0 'dd if=/dev/urandom of=/dev/shm/state bs=1M count=300; dd if=/dev/urandom of=$HOME/state.bin bs=1M count=100; sync'
$RB create --prefix gsrc- --n 1 --kind container --runtime gvisor --cpus 2 --memory-mb 2048 --headless --keep
# same world as above in gsrc-0, then:
for i in $(seq 1 10); do $RB checkpoint --source gsrc-0 --name ckg-$i; done

Cua commands use the published Cua Spaces 0.15.0 release and the public trycua/cua repository at the tag cua-spaces-v0.15.0. Downloads: samples (CSV), result (JSON), this page as Markdown.

Questions

Does the Space stop?

No. Each checkpoint is taken while the Space keeps running.

Can I run this myself?

Yes. The commands under Reproduce use the published Cua Spaces 0.15.0 release and the public trycua/cua repository at the tag cua-spaces-v0.15.0. A `cua bench run` command that wraps them is coming; it isn't in a release yet.

Checked 2026-10-25. Sources: the samples and result files above, measured by Cua. All benchmarks.