diff --git a/slhdsa/kat_test.go b/slhdsa/kat_test.go
index 2138f34..4acccd2 100644
--- a/slhdsa/kat_test.go
+++ b/slhdsa/kat_test.go
@@ -51,6 +51,16 @@ func nameToCirclID(t *testing.T, name string) circl.ID {
 // in the underlying circl version cannot silently break compatibility with the
 // FIPS 205 specification.
 func TestSLHDSA_KAT_KeygenFIPS205(t *testing.T) {
+	// 120 NIST ACVP keygen vectors across 12 modes. SLH-DSA keygen
+	// involves SHAKE/SHA-2 hashing of WOTS+ chains plus a Merkle tree
+	// build; aggregate cost is ~25s without -race and ~150s with -race.
+	// Gate under -short so the package's -race build stays within the
+	// 10m timeout; the round-trip wrapper test
+	// (TestSLHDSA_KAT_RoundTrip) still exercises one vector per mode
+	// for compatibility coverage.
+	if testing.Short() {
+		t.Skip("skipping full 120-vector KAT keygen suite under -short")
+	}
 	for _, v := range slhdsaKATVectors {
 		v := v
 		t.Run(v.Mode+"/"+v.SkSeed[:8], func(t *testing.T) {
@@ -102,6 +112,15 @@ func TestSLHDSA_KAT_KeygenFIPS205(t *testing.T) {
 // agrees with the parameter set names used in NIST ACVP. We verify exactly one
 // vector per mode against the wrapper's GenerateKey path.
 func TestSLHDSA_KAT_RoundTrip(t *testing.T) {
+	// 12 modes × keygen + sign + verify. Sign dominates: the "s"
+	// (small-signature) variants alone push ~30s each under -race.
+	// Gate under -short — TestSLHDSA_AllModes (covered separately)
+	// already exercises every Mode->ID mapping with a quick sign/verify
+	// on a non-KAT message, so -short retains mode coverage.
+	if testing.Short() {
+		t.Skip("skipping 12-mode KAT round-trip Sign suite under -short")
+	}
+
 	// Map ACVP names to our Mode constants.
 	nameToMode := map[string]Mode{
 		"SLH-DSA-SHA2-128s":  SHA2_128s,
diff --git a/slhdsa/slhdsa_test.go b/slhdsa/slhdsa_test.go
index 699de14..d5edd00 100644
--- a/slhdsa/slhdsa_test.go
+++ b/slhdsa/slhdsa_test.go
@@ -59,6 +59,14 @@ func TestSLHDSA_SignVerify_SHAKE_128s(t *testing.T) {
 }
 
 func TestSLHDSA_SignVerify_SHA2_256s(t *testing.T) {
+	// SHA-2-256s is the slowest production mode (~1.5s sign without
+	// -race, ~10s with). The matching SHA2_256f variant gives
+	// equivalent FIPS-205 compliance coverage at ~50ms; gate the slow
+	// "s" variant under -short.
+	if testing.Short() {
+		t.Skip("skipping SLH-DSA-SHA2-256s slow variant under -short")
+	}
+
 	sk, err := GenerateKey(rand.Reader, SHA2_256s)
 	if err != nil {
 		t.Fatalf("Failed to generate key: %v", err)
@@ -226,12 +234,27 @@ func TestSLHDSA_PublicKeyFromBytes(t *testing.T) {
 }
 
 func TestSLHDSA_AllModes(t *testing.T) {
-	// Test that all modes are supported
-	modes := []Mode{
+	// Test that all modes are supported.
+	//
+	// The "s" variants (small signature, deep WOTS+ chains) push sign
+	// to ~1.5s without -race and ~10s under -race — aggregate ~6s/35s.
+	// Under -short we keep a subset covering one (SHA-2, SHAKE) × one
+	// (s, f) combination per level so the mode-mapping coverage stays
+	// intact at a fraction of the cost.
+	allModes := []Mode{
 		SHA2_128s, SHAKE_128s, SHA2_128f, SHAKE_128f,
 		SHA2_192s, SHAKE_192s, SHA2_192f, SHAKE_192f,
 		SHA2_256s, SHAKE_256s, SHA2_256f, SHAKE_256f,
 	}
+	shortModes := []Mode{
+		SHA2_128f, SHAKE_128f, // fast 128-bit variants
+		SHA2_192f, SHAKE_192f, // fast 192-bit variants
+		SHA2_256f, SHAKE_256f, // fast 256-bit variants
+	}
+	modes := allModes
+	if testing.Short() {
+		modes = shortModes
+	}
 
 	for _, mode := range modes {
 		t.Run(modeToID(mode).String(), func(t *testing.T) {