5 files changed, 60 insertions, 13 deletions
diff --git a/plumbing/format/idxfile/idxfile.go b/plumbing/format/idxfile/idxfile.go
index 5fed278..26cca59 100644
--- a/plumbing/format/idxfile/idxfile.go
+++ b/plumbing/format/idxfile/idxfile.go
@@ -55,7 +55,8 @@ type MemoryIndex struct {
 	PackfileChecksum [20]byte
 	IdxChecksum      [20]byte
 
-	offsetHash map[int64]plumbing.Hash
+	offsetHash       map[int64]plumbing.Hash
+	offsetHashIsFull bool
 }
 
 var _ Index = (*MemoryIndex)(nil)
@@ -121,7 +122,17 @@ func (idx *MemoryIndex) FindOffset(h plumbing.Hash) (int64, error) {
 		return 0, plumbing.ErrObjectNotFound
 	}
 
-	return idx.getOffset(k, i)
+	offset, err := idx.getOffset(k, i)
+
+	if !idx.offsetHashIsFull {
+		// Save the offset for reverse lookup
+		if idx.offsetHash == nil {
+			idx.offsetHash = make(map[int64]plumbing.Hash)
+		}
+		idx.offsetHash[offset] = h
+	}
+
+	return offset, err
 }
 
 const isO64Mask = uint64(1) << 31
@@ -167,14 +178,24 @@ func (idx *MemoryIndex) getCRC32(firstLevel, secondLevel int) (uint32, error) {
 
 // FindHash implements the Index interface.
 func (idx *MemoryIndex) FindHash(o int64) (plumbing.Hash, error) {
+	var hash plumbing.Hash
+	var ok bool
+
+	if idx.offsetHash != nil {
+		if hash, ok = idx.offsetHash[o]; ok {
+			return hash, nil
+		}
+	}
+
 	// Lazily generate the reverse offset/hash map if required.
-	if idx.offsetHash == nil {
+	if !idx.offsetHashIsFull || idx.offsetHash == nil {
 		if err := idx.genOffsetHash(); err != nil {
 			return plumbing.ZeroHash, err
 		}
+
+		hash, ok = idx.offsetHash[o]
 	}
 
-	hash, ok := idx.offsetHash[o]
 	if !ok {
 		return plumbing.ZeroHash, plumbing.ErrObjectNotFound
 	}
@@ -190,6 +211,7 @@ func (idx *MemoryIndex) genOffsetHash() error {
 	}
 
 	idx.offsetHash = make(map[int64]plumbing.Hash, count)
+	idx.offsetHashIsFull = true
 
 	iter, err := idx.Entries()
 	if err != nil {
diff --git a/plumbing/object/commit.go b/plumbing/object/commit.go
index b569d3c..511242d 100644
--- a/plumbing/object/commit.go
+++ b/plumbing/object/commit.go
@@ -171,7 +171,9 @@ func (c *Commit) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufio.NewReader(reader)
+	r := bufPool.Get().(*bufio.Reader)
+	defer bufPool.Put(r)
+	r.Reset(reader)
 
 	var message bool
 	var pgpsig bool
diff --git a/plumbing/object/common.go b/plumbing/object/common.go
new file mode 100644
index 0000000..3591f5f
--- /dev/null
+++ b/plumbing/object/common.go
@@ -0,0 +1,12 @@
+package object
+
+import (
+	"bufio"
+	"sync"
+)
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		return bufio.NewReader(nil)
+	},
+}
diff --git a/plumbing/object/tag.go b/plumbing/object/tag.go
index 7f5e406..bc03477 100644
--- a/plumbing/object/tag.go
+++ b/plumbing/object/tag.go
@@ -93,7 +93,9 @@ func (t *Tag) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufio.NewReader(reader)
+	r := bufPool.Get().(*bufio.Reader)
+	defer bufPool.Put(r)
+	r.Reset(reader)
 	for {
 		var line []byte
 		line, err = r.ReadBytes('\n')
diff --git a/plumbing/object/tree.go b/plumbing/object/tree.go
index 1f9ea26..d30cf6e 100644
--- a/plumbing/object/tree.go
+++ b/plumbing/object/tree.go
@@ -230,7 +230,9 @@ func (t *Tree) Decode(o plumbing.EncodedObject) (err error) {
 	}
 	defer ioutil.CheckClose(reader, &err)
 
-	r := bufio.NewReader(reader)
+	r := bufPool.Get().(*bufio.Reader)
+	defer bufPool.Put(r)
+	r.Reset(reader)
 	for {
 		str, err := r.ReadString(' ')
 		if err != nil {
@@ -383,7 +385,7 @@ func NewTreeWalker(t *Tree, recursive bool, seen map[plumbing.Hash]bool) *TreeWa
 // underlying repository will be skipped automatically. It is possible that this
 // may change in future versions.
 func (w *TreeWalker) Next() (name string, entry TreeEntry, err error) {
-	var obj Object
+	var obj *Tree
 	for {
 		current := len(w.stack) - 1
 		if current < 0 {
@@ -403,7 +405,7 @@ func (w *TreeWalker) Next() (name string, entry TreeEntry, err error) {
 			// Finished with the current tree, move back up to the parent
 			w.stack = w.stack[:current]
 			w.base, _ = path.Split(w.base)
-			w.base = path.Clean(w.base) // Remove trailing slash
+			w.base = strings.TrimSuffix(w.base, "/")
 			continue
 		}
 
@@ -419,7 +421,7 @@ func (w *TreeWalker) Next() (name string, entry TreeEntry, err error) {
 			obj, err = GetTree(w.s, entry.Hash)
 		}
 
-		name = path.Join(w.base, entry.Name)
+		name = simpleJoin(w.base, entry.Name)
 
 		if err != nil {
 			err = io.EOF
@@ -433,9 +435,9 @@ func (w *TreeWalker) Next() (name string, entry TreeEntry, err error) {
 		return
 	}
 
-	if t, ok := obj.(*Tree); ok {
-		w.stack = append(w.stack, &treeEntryIter{t, 0})
-		w.base = path.Join(w.base, entry.Name)
+	if obj != nil {
+		w.stack = append(w.stack, &treeEntryIter{obj, 0})
+		w.base = simpleJoin(w.base, entry.Name)
 	}
 
 	return
@@ -509,3 +511,10 @@ func (iter *TreeIter) ForEach(cb func(*Tree) error) error {
 		return cb(t)
 	})
 }
+
+func simpleJoin(parent, child string) string {
+	if len(parent) > 0 {
+		return parent + "/" + child
+	}
+	return child
+}
+\ No newline at end of file