diff --git a/CLAUDE.md b/CLAUDE.md
index 66f8cd7..5ec2e11 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -28,6 +28,7 @@ cargo test --test shader_valid   # just the WGSL parse/validate tests (naga, no
 cargo clippy
 cargo fmt                    # rustfmt.toml just pins edition = "2024"
 cargo build --release --no-default-features   # headless-only binary: no eframe/egui (the default `gui` feature)
+tools/bench/bench.sh --rev HEAD   # perf of uncommitted edits vs HEAD (hyperfine; see tools/bench/README.md)
 ```
 
 Web build (WebGPU):
diff --git a/tools/bench/.gitignore b/tools/bench/.gitignore
new file mode 100644
index 0000000..bd1d75d
--- /dev/null
+++ b/tools/bench/.gitignore
@@ -0,0 +1,2 @@
+results/
+.worktrees/
diff --git a/tools/bench/README.md b/tools/bench/README.md
new file mode 100644
index 0000000..7ce3b8c
--- /dev/null
+++ b/tools/bench/README.md
@@ -0,0 +1,48 @@
+# Benchmarks
+
+`bench.sh` times `mandelbrot --headless` on a fixed set of views with
+[hyperfine](https://github.com/sharkdp/hyperfine). That's the whole real
+pipeline: the reference orbit on the CPU, then the GPU render, readback and PNG
+encode. It builds the headless-only binary (`--no-default-features`) itself.
+
+```sh
+tools/bench/bench.sh --rev HEAD            # did my uncommitted edits help? (vs last commit)
+tools/bench/bench.sh --rev main seahorse-1e300   # one scenario vs another branch
+tools/bench/bench.sh --quick               # all scenarios, 960×540, 3 runs
+tools/bench/bench.sh                       # all scenarios, 1920×1080, 5 runs
+tools/bench/bench.sh --list
+```
+
+`--rev REF` checks REF out into `.worktrees/<sha>` and builds it there, with its
+own target dir, so your `target/` stays warm. Each scenario then runs both
+binaries back to back in one hyperfine call. The line to read is
+`working tree ran 1.23 ± 0.04 times faster than main (…)`. A ratio within about
+2σ of 1.00 is noise.
+
+Results (hyperfine JSON and markdown per scenario) go to
+`results/<sha>[-dirty]/`, or `results/<rev>-vs-<sha>/` with `--rev`.
+Both `results/` and `.worktrees/` are git-ignored. To clean up:
+`rm -rf tools/bench/.worktrees && git worktree prune`.
+
+## Scenarios
+
+| name | mostly measures |
+|---|---|
+| `shallow` | GPU, plain f32 path, f64 orbit fast path |
+| `seahorse-1e30` | GPU f32 perturbation from a `Big` orbit |
+| `seahorse-1e100` | the `DEEP` shader pipeline |
+| `elephant-1e100-aa-de` | 2×2 antialiasing + DE shading |
+| `burning-ship` | a non-holomorphic kind |
+| `3d` | the raymarched 3D export path |
+| `anim-zoom` | 24-frame zoom (⅓ size): the parallel orbit, GPU and PNG pipeline |
+| `seahorse-1e300` *(slow)* | ~270k iterations per pixel on the deep path, ~40 s per run even with `--quick`. It's GPU-bound: the orbit itself is under a second. Only runs when named or with `--all` |
+
+Views come from `tools/deep-zoom/LOCATIONS.md`. Each wall time includes process
+start, device creation and shader compilation, so a small change to a GPU-bound
+scenario shows up diluted.
+
+## Tips
+
+- Keep the machine idle and on AC power. Other GPU apps (browsers, video) add a lot of noise.
+- Use `--quick` while you iterate and a full run to confirm.
+- Timings are only comparable on the same machine and GPU.
diff --git a/tools/bench/bench.sh b/tools/bench/bench.sh
new file mode 100755
index 0000000..59f690e
--- /dev/null
+++ b/tools/bench/bench.sh
@@ -0,0 +1,128 @@
+#!/usr/bin/env bash
+# Benchmark `mandelbrot --headless` on a fixed set of scenarios with hyperfine.
+#
+# Usage:
+#   bench.sh [--quick] [--runs N] [--rev REF] [--all] [--list] [scenario...]
+#
+#   (default)   time the working tree; results go to results/<sha>[-dirty]/
+#   --rev REF   also build REF (in a git worktree) and time both binaries side
+#               by side; hyperfine prints "X ± σ times faster" per scenario
+#   --quick     960×540 and 3 runs instead of 1920×1080 and 5
+#   --runs N    timed runs per command (after 1 warmup run)
+#   --all       include the slow scenarios
+#   --list      print the scenario names and exit
+#
+# With no scenario names, all but the slow ones run. See README.md.
+
+set -euo pipefail
+
+here=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+root=$(git -C "$here" rev-parse --show-toplevel)
+
+# Views from tools/deep-zoom/LOCATIONS.md.
+SEAHORSE_40='-0.77568376800905379745347652613832924487504096622022,0.13646736829469012473375311880735014411233827361594'
+SEAHORSE_101='-0.77568376800905379746948350393474104572824650461579342765769586746577714101553375163935420167637213972439444483,0.13646736829469012473327440961784876519777211159246218448277041663416833530840062457397927487282583495378053495'
+SEAHORSE_300='-0.775683768009053797469483503934741045728246504615800394794952001400666017222819589894883159368782255028252296689050972508942991790804637379375064948276511044167168394677127466362472192356953918438738697548775738756167744421444715134058363508346750264411321139485834882343906172015818621107808449401958194265462,0.136467368294690124733274409617848765197772111592467696407800195400835665974815500875448611244178656625706823059759836009902469392551108149827753781145338163746214967880988693412636771323356061132825037923307975359146666033691080243216637006179374407866237575096209504710178751614036006531433101633993532313930'
+ELEPHANT_100='0.2920738619144539179997175176922057340804018914331633820622644536373359023331882946705674169275530423410817910,0.01577091721139011808246902823033833768260048863232968822435568049949556139801802963232184866659058960379114747'
+
+# name -> headless args (no size or --export-path; those are added per run).
+# Order matters for display, hence the separate list. SLOW ones (tens of
+# seconds per run) only run when named or with --all.
+SCENARIOS=(shallow seahorse-1e30 seahorse-1e100 elephant-1e100-aa-de burning-ship 3d anim-zoom)
+SLOW=(seahorse-1e300)
+declare -A ARGS=(
+    [shallow]="--view=-0.75,0,1.5"
+    [seahorse-1e30]="--view=$SEAHORSE_40,1e-30"
+    [seahorse-1e100]="--view=$SEAHORSE_101,3.4e-101"
+    [seahorse-1e300]="--view=$SEAHORSE_300,5.5e-300"
+    [elephant-1e100-aa-de]="--view=$ELEPHANT_100,1e-75 --antialias --de"
+    [burning-ship]="--kind burning-ship"
+    [3d]="--rendering-kind 3d --de --pitch -40 --view=-0.75,0,1.5"
+    [anim-zoom]="--view=-0.75,0,1.5 --to-view=$SEAHORSE_40,1e-30 --frames 24"
+)
+
+quick=0
+runs=
+rev=
+picked=()
+while (($#)); do
+    case $1 in
+        --quick) quick=1 ;;
+        --runs) runs=$2; shift ;;
+        --rev) rev=$2; shift ;;
+        --all) picked+=("${SCENARIOS[@]}" "${SLOW[@]}") ;;
+        --list) printf '%s\n' "${SCENARIOS[@]}"; printf '%s (slow)\n' "${SLOW[@]}"; exit 0 ;;
+        -h|--help) sed -n '2,16s/^# \{0,1\}//p' "$0"; exit 0 ;;
+        -*) echo "unknown option: $1" >&2; exit 2 ;;
+        *)
+            [[ -v ARGS[$1] ]] || { echo "unknown scenario: $1 (try --list)" >&2; exit 2; }
+            picked+=("$1") ;;
+    esac
+    shift
+done
+((${#picked[@]})) || picked=("${SCENARIOS[@]}")
+
+if ((quick)); then
+    width=960 height=540 runs=${runs:-3}
+else
+    width=1920 height=1080 runs=${runs:-5}
+fi
+
+command -v hyperfine >/dev/null || { echo "hyperfine not found (https://github.com/sharkdp/hyperfine)" >&2; exit 1; }
+
+# Headless-only binary: no eframe/egui, faster to build, same render path.
+build() { cargo build --release --no-default-features --quiet --manifest-path "$1/Cargo.toml"; }
+
+echo "building working tree…" >&2
+build "$root"
+new_bin="$root/target/release/mandelbrot"
+
+if [[ -n $rev ]]; then
+    rev_sha=$(git -C "$root" rev-parse --short "$rev^{commit}")
+    wt="$here/.worktrees/$rev_sha"
+    [[ -d $wt ]] || git -C "$root" worktree add --detach --quiet "$wt" "$rev_sha"
+    echo "building $rev ($rev_sha)…" >&2
+    # Separate target dir so switching revisions doesn't invalidate target/.
+    CARGO_TARGET_DIR="$here/.worktrees/target" build "$wt"
+    old_bin="$here/.worktrees/target/release/mandelbrot"
+fi
+
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
+
+sha=$(git -C "$root" rev-parse --short HEAD)
+git -C "$root" diff --quiet HEAD -- . ':!tools/bench' || sha+=-dirty
+out="$here/results/${rev:+$rev_sha-vs-}$sha"
+mkdir -p "$out"
+
+# Full headless command line for scenario $2 with binary $1.
+command_for() {
+    local bin=$1 name=$2 w=$width h=$height dest=$tmp/$2.png
+    if [[ $name == anim-* ]]; then
+        # Animation: a directory of frames, at a smaller size.
+        w=$((width / 3)) h=$((height / 3)) dest=$tmp/$name
+    fi
+    echo "$bin --headless --width $w --height $h --export-path $dest ${ARGS[$name]}"
+}
+
+for name in "${picked[@]}"; do
+    echo >&2
+    echo "=== $name ===" >&2
+    if [[ -n $rev ]]; then
+        cmds=(-n "$rev ($rev_sha)" "$(command_for "$old_bin" "$name")"
+              -n "working tree" "$(command_for "$new_bin" "$name")")
+    else
+        cmds=(-n "$name" "$(command_for "$new_bin" "$name")")
+    fi
+    hyperfine --warmup 1 --runs "$runs" --style basic \
+        --export-json "$out/$name.json" --export-markdown "$out/$name.md" \
+        "${cmds[@]}"
+done
+
+echo
+echo "## Summary (${width}×${height}, $runs runs; results in ${out#"$root"/}/)"
+for name in "${picked[@]}"; do
+    echo
+    echo "### $name"
+    cat "$out/$name.md"
+done