src/archive/zip/reader.go      | 11 ++++++++++-
 src/archive/zip/reader_test.go | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++

diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
index 2246d56558bbeea48ea23c3214eaca7d4afaf615..0c48a7857d4f695738ab4f775a8809cfe8fdc273 100644
--- a/src/archive/zip/reader.go
+++ b/src/archive/zip/reader.go
@@ -830,7 +830,16 @@ 				r.fileList[idx].isDup = true
 				continue
 			}
 
-			for dir := path.Dir(name); dir != "."; dir = path.Dir(dir) {
+			dir := name
+			for {
+				if idx := strings.LastIndex(dir, "/"); idx < 0 {
+					break
+				} else {
+					dir = dir[:idx]
+				}
+				if dirs[dir] {
+					break
+				}
 				dirs[dir] = true
 			}
 
diff --git a/src/archive/zip/reader_test.go b/src/archive/zip/reader_test.go
index bfa35c992a924c0717e473c57b9c9f8d6f2d6500..9fdb5e3eba9a969ad0b731b2c0ea4939e95967af 100644
--- a/src/archive/zip/reader_test.go
+++ b/src/archive/zip/reader_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"encoding/hex"
+	"fmt"
 	"internal/obscuretestdata"
 	"io"
 	"io/fs"
@@ -1832,3 +1833,83 @@ 	// an io.SectionReader which would access a slice at a negative offset
 	// as the section reader offset & size were < 0.
 	NewReader(bytes.NewReader(data), int64(len(data))+1875)
 }
+
+func BenchmarkReaderOneDeepDir(b *testing.B) {
+	var buf bytes.Buffer
+	zw := NewWriter(&buf)
+
+	for i := range 4000 {
+		name := strings.Repeat("a/", i) + "data"
+		zw.CreateHeader(&FileHeader{
+			Name:   name,
+			Method: Store,
+		})
+	}
+
+	if err := zw.Close(); err != nil {
+		b.Fatal(err)
+	}
+	data := buf.Bytes()
+
+	for b.Loop() {
+		zr, err := NewReader(bytes.NewReader(data), int64(len(data)))
+		if err != nil {
+			b.Fatal(err)
+		}
+		zr.Open("does-not-exist")
+	}
+}
+
+func BenchmarkReaderManyDeepDirs(b *testing.B) {
+	var buf bytes.Buffer
+	zw := NewWriter(&buf)
+
+	for i := range 2850 {
+		name := fmt.Sprintf("%x", i)
+		name = strings.Repeat("/"+name, i+1)[1:]
+
+		zw.CreateHeader(&FileHeader{
+			Name:   name,
+			Method: Store,
+		})
+	}
+
+	if err := zw.Close(); err != nil {
+		b.Fatal(err)
+	}
+	data := buf.Bytes()
+
+	for b.Loop() {
+		zr, err := NewReader(bytes.NewReader(data), int64(len(data)))
+		if err != nil {
+			b.Fatal(err)
+		}
+		zr.Open("does-not-exist")
+	}
+}
+
+func BenchmarkReaderManyShallowFiles(b *testing.B) {
+	var buf bytes.Buffer
+	zw := NewWriter(&buf)
+
+	for i := range 310000 {
+		name := fmt.Sprintf("%v", i)
+		zw.CreateHeader(&FileHeader{
+			Name:   name,
+			Method: Store,
+		})
+	}
+
+	if err := zw.Close(); err != nil {
+		b.Fatal(err)
+	}
+	data := buf.Bytes()
+
+	for b.Loop() {
+		zr, err := NewReader(bytes.NewReader(data), int64(len(data)))
+		if err != nil {
+			b.Fatal(err)
+		}
+		zr.Open("does-not-exist")
+	}
+}