diff --git a/pkg/mmap/mmap_unix.go b/pkg/mmap/mmap_unix.go
index c9faafb8d4c..13629c1a4e5 100644
--- a/pkg/mmap/mmap_unix.go
+++ b/pkg/mmap/mmap_unix.go
@@ -10,7 +10,6 @@ package mmap
 import (
 	"os"
 	"syscall"
-	"unsafe"
 )
 
 // Map memory-maps a file.
@@ -38,11 +37,6 @@ func Map(path string, sz int64) ([]byte, error) {
 		return nil, err
 	}
 
-	if _, _, err := syscall.Syscall(syscall.SYS_MADVISE, uintptr(unsafe.Pointer(&data[0])), uintptr(len(data)), uintptr(syscall.MADV_RANDOM)); err != 0 {
-		Unmap(data)
-		return nil, err
-	}
-
 	return data, nil
 }
 
diff --git a/pkg/rhh/rhh.go b/pkg/rhh/rhh.go
index 05307159008..bb8db4be7cb 100644
--- a/pkg/rhh/rhh.go
+++ b/pkg/rhh/rhh.go
@@ -19,6 +19,8 @@ type HashMap struct {
 	threshold  int64
 	mask       int64
 	loadFactor int
+
+	tmpKey []byte
 }
 
 func NewHashMap(opt Options) *HashMap {
@@ -65,16 +67,19 @@ func (m *HashMap) insert(hash int64, key []byte, val interface{}) (overwritten b
 	pos := hash & m.mask
 	var dist int64
 
+	var copied bool
+	searchKey := key
+
 	// Continue searching until we find an empty slot or lower probe distance.
 	for {
 		e := &m.elems[pos]
 
 		// Empty slot found or matching key, insert and exit.
-		match := bytes.Equal(m.elems[pos].key, key)
+		match := bytes.Equal(m.elems[pos].key, searchKey)
 		if m.hashes[pos] == 0 || match {
 			m.hashes[pos] = hash
 			e.hash, e.value = hash, val
-			e.setKey(key)
+			e.setKey(searchKey)
 			return match
 		}
 
@@ -86,11 +91,16 @@ func (m *HashMap) insert(hash int64, key []byte, val interface{}) (overwritten b
 			hash, m.hashes[pos] = m.hashes[pos], hash
 			val, e.value = e.value, val
 
-			tmp := make([]byte, len(e.key))
-			copy(tmp, e.key)
+			m.tmpKey = assign(m.tmpKey, e.key)
+			e.setKey(searchKey)
 
-			e.setKey(key)
-			key = tmp
+			if !copied {
+				searchKey = make([]byte, len(key))
+				copy(searchKey, key)
+				copied = true
+			}
+
+			searchKey = assign(searchKey, m.tmpKey)
 
 			// Update current distance.
 			dist = elemDist
@@ -208,15 +218,7 @@ func (e *hashElem) reset() {
 
 // setKey copies v to a key on e.
 func (e *hashElem) setKey(v []byte) {
-	// Shrink or grow key to fit value.
-	if len(e.key) > len(v) {
-		e.key = e.key[:len(v)]
-	} else if len(e.key) < len(v) {
-		e.key = append(e.key, make([]byte, len(v)-len(e.key))...)
-	}
-
-	// Copy value to key.
-	copy(e.key, v)
+	e.key = assign(e.key, v)
 }
 
 // Options represents initialization options that are passed to NewHashMap().
@@ -268,6 +270,15 @@ func pow2(v int64) int64 {
 	panic("unreachable")
 }
 
+func assign(x, v []byte) []byte {
+	if cap(x) < len(v) {
+		x = make([]byte, len(v))
+	}
+	x = x[:len(v)]
+	copy(x, v)
+	return x
+}
+
 type byteSlices [][]byte
 
 func (a byteSlices) Len() int           { return len(a) }
diff --git a/tsdb/engine/tsm1/mmap_unix.go b/tsdb/engine/tsm1/mmap_unix.go
index d4c7b2b3e29..48b4a8caef3 100644
--- a/tsdb/engine/tsm1/mmap_unix.go
+++ b/tsdb/engine/tsm1/mmap_unix.go
@@ -27,6 +27,10 @@ func munmap(b []byte) (err error) {
 	return unix.Munmap(b)
 }
 
+func madviseWillNeed(b []byte) error {
+	return madvise(b, syscall.MADV_WILLNEED)
+}
+
 func madviseDontNeed(b []byte) error {
 	return madvise(b, syscall.MADV_DONTNEED)
 }
diff --git a/tsdb/engine/tsm1/mmap_windows.go b/tsdb/engine/tsm1/mmap_windows.go
index 360be3efe8d..1991f841f42 100644
--- a/tsdb/engine/tsm1/mmap_windows.go
+++ b/tsdb/engine/tsm1/mmap_windows.go
@@ -121,6 +121,10 @@ func munmap(b []byte) (err error) {
 	return nil
 }
 
+func madviseWillNeed(b []byte) error {
+	return nil
+}
+
 func madviseDontNeed(b []byte) error {
 	// Not supported
 	return nil
diff --git a/tsdb/engine/tsm1/reader.go b/tsdb/engine/tsm1/reader.go
index b3b13bd0838..aeb3747c5a9 100644
--- a/tsdb/engine/tsm1/reader.go
+++ b/tsdb/engine/tsm1/reader.go
@@ -1374,6 +1374,10 @@ func (m *mmapAccessor) init() (*indirectIndex, error) {
 		return nil, fmt.Errorf("mmapAccessor: invalid indexStart")
 	}
 
+	// Hint to the kernal that we will be reading the file.  It would be better to hint
+	// that we will be reading the index section, but that doesn't seem to work ATM.
+	_ = madviseWillNeed(m.b)
+
 	m.index = NewIndirectIndex()
 	if err := m.index.UnmarshalBinary(m.b[indexStart:indexOfsPos]); err != nil {
 		return nil, err
diff --git a/tsdb/index/tsi1/log_file.go b/tsdb/index/tsi1/log_file.go
index 3296f6ce4a3..245acccb3e8 100644
--- a/tsdb/index/tsi1/log_file.go
+++ b/tsdb/index/tsi1/log_file.go
@@ -36,13 +36,14 @@ const (
 
 // LogFile represents an on-disk write-ahead log file.
 type LogFile struct {
-	mu   sync.RWMutex
-	wg   sync.WaitGroup // ref count
-	id   int            // file sequence identifier
-	data []byte         // mmap
-	file *os.File       // writer
-	w    *bufio.Writer  // buffered writer
-	buf  []byte         // marshaling buffer
+	mu     sync.RWMutex
+	wg     sync.WaitGroup // ref count
+	id     int            // file sequence identifier
+	data   []byte         // mmap
+	file   *os.File       // writer
+	w      *bufio.Writer  // buffered writer
+	buf    []byte         // marshaling buffer
+	keyBuf []byte
 
 	sfile   *tsdb.SeriesFile // series lookup
 	size    int64            // tracks current file size
@@ -478,7 +479,7 @@ func (f *LogFile) AddSeriesList(seriesSet *tsdb.SeriesIDSet, names [][]byte, tag
 			continue
 		}
 		writeRequired = true
-		entries = append(entries, LogEntry{SeriesID: seriesIDs[i]})
+		entries = append(entries, LogEntry{SeriesID: seriesIDs[i], name: names[i], tags: tagsSlice[i], cached: true})
 	}
 	seriesSet.RUnlock()
 
@@ -607,7 +608,17 @@ func (f *LogFile) execDeleteTagValueEntry(e *LogEntry) {
 }
 
 func (f *LogFile) execSeriesEntry(e *LogEntry) {
-	seriesKey := f.sfile.SeriesKey(e.SeriesID)
+	var seriesKey []byte
+	if e.cached {
+		sz := tsdb.SeriesKeySize(e.name, e.tags)
+		if len(f.keyBuf) < sz {
+			f.keyBuf = make([]byte, 0, sz)
+		}
+		seriesKey = tsdb.AppendSeriesKey(f.keyBuf[:0], e.name, e.tags)
+	} else {
+		seriesKey = f.sfile.SeriesKey(e.SeriesID)
+	}
+
 	assert(seriesKey != nil, fmt.Sprintf("series key for ID: %d not found", e.SeriesID))
 
 	// Check if deleted.
@@ -966,6 +977,10 @@ type LogEntry struct {
 	Value    []byte // tag value
 	Checksum uint32 // checksum of flag/name/tags.
 	Size     int    // total size of record, in bytes.
+
+	cached bool        // Hint to LogFile that series data is already parsed
+	name   []byte      // series naem, this is a cached copy of the parsed measurement name
+	tags   models.Tags // series tags, this is a cached copied of the parsed tags
 }
 
 // UnmarshalBinary unmarshals data into e.