diff --git a/lite/helpers.go b/lite/helpers.go
index fc4d697a..d985882d 100644
--- a/lite/helpers.go
+++ b/lite/helpers.go
@@ -77,10 +77,7 @@ func (v ValKeys) signHeader(header *types.Header, first, last int) *types.Commit
 	vset := v.ToValidators(1, 0)
 
 	// fill in the votes we want
-	for i := first; i < last; i++ {
-		if i >= len(v) {
-			break
-		}
+	for i := first; i < last && i < len(v); i++ {
 		vote := makeVote(header, vset, v[i])
 		votes[vote.ValidatorIndex] = vote
 	}
diff --git a/lite/memprovider.go b/lite/memprovider.go
index bfd260ce..574aed8d 100644
--- a/lite/memprovider.go
+++ b/lite/memprovider.go
@@ -60,8 +60,8 @@ func (m *memStoreProvider) StoreCommit(fc FullCommit) error {
 
 // GetByHeight returns the FullCommit for height h or an error if the commit is not found.
 func (m *memStoreProvider) GetByHeight(h int64) (FullCommit, error) {
-	m.mtx.RLock()
-	defer m.mtx.RUnlock()
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
 	if !m.sorted {
 		sort.Sort(m.byHeight)
 		m.sorted = true
@@ -77,8 +77,8 @@ func (m *memStoreProvider) GetByHeight(h int64) (FullCommit, error) {
 
 // GetByHeight returns the FullCommit for height h or an error if the commit is not found.
 func (m *memStoreProvider) GetByHeightBinarySearch(h int64) (FullCommit, error) {
-	m.mtx.RLock()
-	defer m.mtx.RUnlock()
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
 	if !m.sorted {
 		sort.Sort(m.byHeight)
 		m.sorted = true
diff --git a/lite/performance_test.go b/lite/performance_test.go
index e9167129..da5ead84 100644
--- a/lite/performance_test.go
+++ b/lite/performance_test.go
@@ -3,6 +3,7 @@ package lite_test
 import (
 	"fmt"
 	"math/rand"
+	"sync"
 	"testing"
 
 	"github.com/tendermint/tendermint/lite"
@@ -124,13 +125,20 @@ const (
 	binarySearch = false
 )
 
-var (
-	fcs5, h5       = genFullCommits(nil, nil, 5)
-	fcs50, h50     = genFullCommits(fcs5, h5, 50)
-	fcs100, h100   = genFullCommits(fcs50, h50, 100)
-	fcs500, h500   = genFullCommits(fcs100, h100, 500)
-	fcs1000, h1000 = genFullCommits(fcs500, h500, 1000)
-)
+// Lazy load the commits
+var fcs5, fcs50, fcs100, fcs500, fcs1000 []lite.FullCommit
+var h5, h50, h100, h500, h1000 []int64
+var commitsOnce sync.Once
+
+func lazyGenerateFullCommits() {
+	commitsOnce.Do(func() {
+		fcs5, h5 = genFullCommits(nil, nil, 5)
+		fcs50, h50 = genFullCommits(fcs5, h5, 50)
+		fcs100, h100 = genFullCommits(fcs50, h50, 100)
+		fcs500, h500 = genFullCommits(fcs100, h100, 500)
+		fcs1000, h1000 = genFullCommits(fcs500, h500, 1000)
+	})
+}
 
 func BenchmarkMemStoreProviderGetByHeightLinearSearch5(b *testing.B) {
 	benchmarkMemStoreProviderGetByHeight(b, fcs5, h5, linearSearch)
@@ -175,6 +183,8 @@ func BenchmarkMemStoreProviderGetByHeightBinarySearch1000(b *testing.B) {
 var rng = rand.New(rand.NewSource(10))
 
 func benchmarkMemStoreProviderGetByHeight(b *testing.B, fcs []lite.FullCommit, fHeights []int64, algo algo) {
+	lazyGenerateFullCommits()
+
 	b.StopTimer()
 	mp := lite.NewMemStoreProvider()
 	for i, fc := range fcs {