diff --git a/TODO.md b/TODO.md
index 02f2cf9..37ea5a0 100644
--- a/TODO.md
+++ b/TODO.md
@@ -18,6 +18,22 @@ https://git.eeqj.de/sneak/secret/milestone/12
 
 # Completed Steps
 
+- 2026-10-06: The tests run quickly with the race detector on
+  (https://git.eeqj.de/sneak/secret/issues/120). Most of their time went to
+  deriving keys from passphrases with scrypt, which is slow on purpose. The new
+  `secret.ScryptWorkFactor`, when not zero, replaces age's scrypt work factor
+  when a passphrase encrypts; the tests of `internal/secret`, `internal/vault`
+  and `internal/cli` set it to 1 before any test runs, and the program never
+  sets it; `TestGetCommandOutputsToStdout` checks that the passphrase unlocker
+  the built binary's `secret init` writes names age's work factor, 18.
+  `TestRemovalAsksWithoutHoldingLock` and `TestFailedCommandReleasesLock` no
+  longer run in parallel with other tests: each waits at most 10 seconds for the
+  in-memory lock that every test in the package shares, and other tests'
+  commands held it longer. `TestConcurrentAddsKeepEveryVersion`, which times
+  nothing, and `TestGetCommandOutputsToStdout`, which no longer sets an
+  environment variable its commands do not read, now run in parallel. The
+  `script/cibuild` comment no longer says that tests are skipped without its
+  memlock ulimit.
 - 2026-10-05: No test stores a secret larger than 1 MiB
   (https://git.eeqj.de/sneak/secret/issues/52). The size tests for `secret add`,
   `secret import` and the stdin buffer no longer try 2 MB, 10 MB, 99 MB, 100 MB
diff --git a/internal/cli/confirm_test.go b/internal/cli/confirm_test.go
index 32a56b8..af2ec91 100644
--- a/internal/cli/confirm_test.go
+++ b/internal/cli/confirm_test.go
@@ -353,9 +353,9 @@ func TestRemovalWithoutTerminalFailsAtOnce(t *testing.T) {
 // for its answer, another command can take the state directory lock and
 // change the secret, and that the removal then removes nothing, since the
 // secret is no longer what the question named.
+//
+//nolint:paralleltest // times commands against the in-memory lock all tests share
 func TestRemovalAsksWithoutHoldingLock(t *testing.T) {
-	t.Parallel()
-
 	r := newRemoval(t, "rm")
 
 	answers, answerWriter := io.Pipe()
diff --git a/internal/cli/integration_test.go b/internal/cli/integration_test.go
index d572e5c..9e66629 100644
--- a/internal/cli/integration_test.go
+++ b/internal/cli/integration_test.go
@@ -52,8 +52,12 @@ func runSecretWithStdin(stdin string, env map[string]string, args ...string) (st
 	return cli.ExecuteCommandInProcess(args, stdin, env)
 }
 
-// TestMain runs before all tests and ensures the binary is built
+// TestMain runs before all tests and ensures the binary is built. It also
+// makes passphrase encryption in the tests cheap (see
+// secret.ScryptWorkFactor); the binary keeps age's work factor.
 func TestMain(m *testing.M) {
+	secret.ScryptWorkFactor = 1
+
 	// Get the current working directory
 	wd, err := os.Getwd()
 	if err != nil {
diff --git a/internal/cli/lock_test.go b/internal/cli/lock_test.go
index 502553f..caa2ee3 100644
--- a/internal/cli/lock_test.go
+++ b/internal/cli/lock_test.go
@@ -94,9 +94,9 @@ func numbered(prefix string, count int) []string {
 // lock, adds of a new secret all find it absent and replace each other, and
 // forced adds read the same highest version number and overwrite each
 // other's version. With it they behave as if run one after another.
-//
-//nolint:paralleltest // times commands against the in-memory lock all tests share
 func TestConcurrentAddsKeepEveryVersion(t *testing.T) {
+	t.Parallel()
+
 	mnemonic := testMnemonicBuffer(t)
 
 	const adds = 8
@@ -110,6 +110,8 @@ func TestConcurrentAddsKeepEveryVersion(t *testing.T) {
 		{"real", afero.NewOsFs(), t.TempDir()},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
 			_, err := vault.CreateVault(tc.fs, tc.stateDir, "default", mnemonic, nil)
 			require.NoError(t, err)
 
@@ -235,9 +237,9 @@ func TestEncryptPipedIntoAdd(t *testing.T) {
 
 // TestFailedCommandReleasesLock checks that a command failing after it
 // took the state directory lock leaves the lock free for the next command.
+//
+//nolint:paralleltest // times commands against the in-memory lock all tests share
 func TestFailedCommandReleasesLock(t *testing.T) {
-	t.Parallel()
-
 	fs := afero.NewMemMapFs()
 	cli := NewCLIInstanceWithStateDir(fs, testStateDir)
 
diff --git a/internal/cli/stdout_stderr_test.go b/internal/cli/stdout_stderr_test.go
index a0916ce..f1937fc 100644
--- a/internal/cli/stdout_stderr_test.go
+++ b/internal/cli/stdout_stderr_test.go
@@ -15,11 +15,11 @@ import (
 // TestGetCommandOutputsToStdout tests that 'secret get' outputs the secret
 // value to stdout, not stderr
 func TestGetCommandOutputsToStdout(t *testing.T) {
-	// Create a temporary directory for our vault
-	tempDir := t.TempDir()
+	t.Parallel()
 
-	// Set environment variables for the test
-	t.Setenv(secret.EnvStateDir, tempDir)
+	// Create a temporary directory for our vault; each command is given it
+	// in its environment
+	tempDir := t.TempDir()
 
 	// Find the secret binary path
 	wd, err := filepath.Abs("../..")
@@ -41,6 +41,18 @@ func TestGetCommandOutputsToStdout(t *testing.T) {
 	output, err := cmd.CombinedOutput()
 	require.NoError(t, err, "init should succeed: %s", string(output))
 
+	// The binary, unlike these tests, encrypts the passphrase unlocker's key
+	// at age's scrypt work factor, 18. age writes the work factor last on the
+	// second line of priv.age: "-> scrypt <salt> <work factor>".
+	vaultDir := filepath.Join(tempDir, "vaults.d", "default")
+	unlockerName := readFile(t, filepath.Join(vaultDir, "current-unlocker"))
+	unlockerDir := filepath.Join(vaultDir, "unlockers.d", string(unlockerName))
+	privAge := readFile(t, filepath.Join(unlockerDir, "priv.age"))
+	header := strings.SplitN(string(privAge), "\n", 3)
+	require.Len(t, header, 3, "priv.age should start with an age header")
+	assert.Regexp(t, `^-> scrypt \S+ 18$`, header[1],
+		"the passphrase unlocker should be encrypted at scrypt work factor 18")
+
 	// Add a secret
 	//nolint:gosec // G204: test executes the freshly built secret binary
 	cmd = exec.CommandContext(t.Context(), secretPath, "add", "test/secret")
diff --git a/internal/secret/crypto.go b/internal/secret/crypto.go
index 9c017a1..f6005f0 100644
--- a/internal/secret/crypto.go
+++ b/internal/secret/crypto.go
@@ -28,6 +28,17 @@ var (
 // terminal to read the mnemonic from, reading it failed, or it was empty.
 var ErrMnemonicNotRead = errors.New("failed to read mnemonic")
 
+// ScryptWorkFactor is, when not zero, the scrypt work factor that
+// EncryptWithPassphrase uses instead of age's, 18: log2 of scrypt's cost
+// parameter N. Deriving a key with age's takes about a second and 256 MiB, on
+// purpose, since so does every guess at the passphrase. Only tests set it,
+// lower, before any test runs, so that the passphrase unlockers they create
+// cost nothing; the program leaves it zero. Decryption takes the work factor
+// from the encrypted data, so it needs no setting.
+//
+//nolint:gochecknoglobals // set by the tests of the packages that use this one
+var ScryptWorkFactor int
+
 // EncryptToRecipient encrypts data to a recipient using age
 // The data parameter should be a LockedBuffer for secure memory handling
 func EncryptToRecipient(
@@ -142,6 +153,10 @@ func EncryptWithPassphrase(
 		return nil, fmt.Errorf("failed to create scrypt recipient: %w", err)
 	}
 
+	if ScryptWorkFactor != 0 {
+		recipient.SetWorkFactor(ScryptWorkFactor)
+	}
+
 	return EncryptToRecipient(data, recipient)
 }
 
diff --git a/internal/secret/secret_test.go b/internal/secret/secret_test.go
index e5dae85..94bd5d4 100644
--- a/internal/secret/secret_test.go
+++ b/internal/secret/secret_test.go
@@ -25,6 +25,14 @@ var (
 	errNotImplementedInMock = errors.New("not implemented in mock")
 )
 
+// TestMain makes passphrase encryption in the tests cheap; see
+// ScryptWorkFactor.
+func TestMain(m *testing.M) {
+	ScryptWorkFactor = 1
+
+	os.Exit(m.Run())
+}
+
 // MockVault is a test implementation of the VaultInterface
 type MockVault struct {
 	name            string
diff --git a/internal/vault/vault_test.go b/internal/vault/vault_test.go
index 2b6967d..72e0243 100644
--- a/internal/vault/vault_test.go
+++ b/internal/vault/vault_test.go
@@ -3,6 +3,7 @@ package vault_test
 import (
 	"bytes"
 	"errors"
+	"os"
 	"path/filepath"
 	"slices"
 	"testing"
@@ -28,6 +29,14 @@ const (
 	testPassphrase = "test-passphrase"
 )
 
+// TestMain makes passphrase encryption in the tests cheap; see
+// secret.ScryptWorkFactor.
+func TestMain(m *testing.M) {
+	secret.ScryptWorkFactor = 1
+
+	os.Exit(m.Run())
+}
+
 // testMnemonicBuffer returns testMnemonic in a locked buffer that is
 // destroyed when the test ends.
 func testMnemonicBuffer(t *testing.T) *memguard.LockedBuffer {
diff --git a/script/cibuild b/script/cibuild
index 58bf15f..bb21515 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -1,9 +1,9 @@
 #!/bin/sh
 # script/cibuild: run the CI build. The Dockerfile runs script/check
 # (via make check), so a successful build implies all checks pass.
-# The Gitea workflow runs this on push. The memlock ulimit lets the tests
-# that lock large secrets in memory (memguard mlocks them) run; under the
-# lower limit of a plain `docker build .` they are skipped.
+# The Gitea workflow runs this on push. The memlock ulimit lifts the limit
+# on memory the tests lock (memguard mlocks secrets); they also pass under
+# the lower limit of a plain `docker build .`.
 # A cached build checks nothing: a new CHECK_EPOCH on every run makes the
 # Dockerfile's check steps run again on an unchanged tree, while its base
 # images and module downloads stay cached.