diff --git a/slices/slices.go b/slices/slices.go
index cff0cd4..2540bd6 100644
--- a/slices/slices.go
+++ b/slices/slices.go
@@ -104,8 +104,8 @@
 // Index returns the index of the first occurrence of v in s,
 // or -1 if not present.
 func Index[E comparable](s []E, v E) int {
-	for i, vs := range s {
-		if v == vs {
+	for i := range s {
+		if v == s[i] {
 			return i
 		}
 	}
@@ -115,8 +115,8 @@
 // IndexFunc returns the first index i satisfying f(s[i]),
 // or -1 if none do.
 func IndexFunc[E any](s []E, f func(E) bool) int {
-	for i, v := range s {
-		if f(v) {
+	for i := range s {
+		if f(s[i]) {
 			return i
 		}
 	}
@@ -207,12 +207,12 @@
 		return s
 	}
 	i := 1
-	last := s[0]
-	for _, v := range s[1:] {
-		if v != last {
-			s[i] = v
+	for k := 1; k < len(s); k++ {
+		if s[k] != s[k-1] {
+			if i != k {
+				s[i] = s[k]
+			}
 			i++
-			last = v
 		}
 	}
 	return s[:i]
@@ -224,12 +224,12 @@
 		return s
 	}
 	i := 1
-	last := s[0]
-	for _, v := range s[1:] {
-		if !eq(v, last) {
-			s[i] = v
+	for k := 1; k < len(s); k++ {
+		if !eq(s[k], s[k-1]) {
+			if i != k {
+				s[i] = s[k]
+			}
 			i++
-			last = v
 		}
 	}
 	return s[:i]
diff --git a/slices/slices_test.go b/slices/slices_test.go
index 1d9ffd2..6ecd822 100644
--- a/slices/slices_test.go
+++ b/slices/slices_test.go
@@ -126,6 +126,16 @@
 	}
 }
 
+func BenchmarkEqualFunc_Large(b *testing.B) {
+	type Large [4 * 1024]byte
+
+	xs := make([]Large, 1024)
+	ys := make([]Large, 1024)
+	for i := 0; i < b.N; i++ {
+		_ = EqualFunc(xs, ys, func(x, y Large) bool { return x == y })
+	}
+}
+
 var compareIntTests = []struct {
 	s1, s2 []int
 	want   int
@@ -334,6 +344,15 @@
 	}
 }
 
+func BenchmarkIndex_Large(b *testing.B) {
+	type Large [4 * 1024]byte
+
+	ss := make([]Large, 1024)
+	for i := 0; i < b.N; i++ {
+		_ = Index(ss, Large{1})
+	}
+}
+
 func TestIndexFunc(t *testing.T) {
 	for _, test := range indexTests {
 		if got := IndexFunc(test.s, equalToIndex(equal[int], test.v)); got != test.want {
@@ -350,6 +369,17 @@
 	}
 }
 
+func BenchmarkIndexFunc_Large(b *testing.B) {
+	type Large [4 * 1024]byte
+
+	ss := make([]Large, 1024)
+	for i := 0; i < b.N; i++ {
+		_ = IndexFunc(ss, func(e Large) bool {
+			return e == Large{1}
+		})
+	}
+}
+
 func TestContains(t *testing.T) {
 	for _, test := range indexTests {
 		if got := Contains(test.s, test.v); got != (test.want != -1) {
@@ -572,7 +602,15 @@
 			}
 		})
 	}
+}
 
+func BenchmarkCompact_Large(b *testing.B) {
+	type Large [4 * 1024]byte
+
+	ss := make([]Large, 1024)
+	for i := 0; i < b.N; i++ {
+		_ = Compact(ss)
+	}
 }
 
 func TestCompactFunc(t *testing.T) {
@@ -591,6 +629,15 @@
 	}
 }
 
+func BenchmarkCompactFunc_Large(b *testing.B) {
+	type Large [4 * 1024]byte
+
+	ss := make([]Large, 1024)
+	for i := 0; i < b.N; i++ {
+		_ = CompactFunc(ss, func(a, b Large) bool { return a == b })
+	}
+}
+
 func TestGrow(t *testing.T) {
 	s1 := []int{1, 2, 3}