diff --git a/fsm.go b/fsm.go
index 2355c68bd..6ed5c0cfc 100644
--- a/fsm.go
+++ b/fsm.go
@@ -211,6 +211,8 @@ func planCommitting(events []statemachine.Event, state *SectorInfo) error {
 			state.State = api.SealCommitFailed
 		case SectorSealFailed:
 			state.State = api.CommitFailed
+		case SectorCommitFailed:
+			state.State = api.CommitFailed
 		default:
 			return xerrors.Errorf("planCommitting got event of unknown type %T, events: %+v", event.User, events)
 		}
diff --git a/fsm_test.go b/fsm_test.go
index 2dada5470..7430bb634 100644
--- a/fsm_test.go
+++ b/fsm_test.go
@@ -83,3 +83,17 @@ func TestSeedRevert(t *testing.T) {
 	m.planSingle(SectorProving{})
 	require.Equal(m.t, m.state.State, api.Proving)
 }
+
+func TestPlanCommittingHandlesSectorCommitFailed(t *testing.T) {
+	m := test{
+		s:     &Sealing{},
+		t:     t,
+		state: &SectorInfo{State: api.Committing},
+	}
+
+	events := []statemachine.Event{{SectorCommitFailed{}}}
+
+	require.NoError(t, planCommitting(events, m.state))
+
+	require.Equal(t, api.SectorStates[api.CommitFailed], api.SectorStates[m.state.State])
+}
diff --git a/garbage.go b/garbage.go
index 32dff004f..2173759d2 100644
--- a/garbage.go
+++ b/garbage.go
@@ -6,6 +6,7 @@ import (
 	"io"
 	"math"
 	"math/rand"
+	"runtime"
 
 	sectorbuilder "github.com/filecoin-project/go-sectorbuilder"
 	"golang.org/x/xerrors"
@@ -14,6 +15,17 @@ import (
 	"github.com/filecoin-project/lotus/chain/types"
 )
 
+func (m *Sealing) pledgeReader(size uint64, parts uint64) io.Reader {
+	piece := sectorbuilder.UserBytesForSectorSize((size/127 + size) / parts)
+
+	readers := make([]io.Reader, parts)
+	for i := range readers {
+		readers[i] = io.LimitReader(rand.New(rand.NewSource(42+int64(i))), int64(piece))
+	}
+
+	return io.MultiReader(readers...)
+}
+
 func (m *Sealing) pledgeSector(ctx context.Context, sectorID uint64, existingPieceSizes []uint64, sizes ...uint64) ([]Piece, error) {
 	if len(sizes) == 0 {
 		return nil, nil
@@ -21,10 +33,7 @@ func (m *Sealing) pledgeSector(ctx context.Context, sectorID uint64, existingPie
 
 	deals := make([]actors.StorageDealProposal, len(sizes))
 	for i, size := range sizes {
-		release := m.sb.RateLimit()
-		commP, err := sectorbuilder.GeneratePieceCommitment(io.LimitReader(rand.New(rand.NewSource(42)), int64(size)), size)
-		release()
-
+		commP, err := m.fastPledgeCommitment(size, uint64(runtime.NumCPU()))
 		if err != nil {
 			return nil, err
 		}
@@ -81,7 +90,7 @@ func (m *Sealing) pledgeSector(ctx context.Context, sectorID uint64, existingPie
 	out := make([]Piece, len(sizes))
 
 	for i, size := range sizes {
-		ppi, err := m.sb.AddPiece(ctx, size, sectorID, io.LimitReader(rand.New(rand.NewSource(42)), int64(size)), existingPieceSizes)
+		ppi, err := m.sb.AddPiece(ctx, size, sectorID, m.pledgeReader(size, uint64(runtime.NumCPU())), existingPieceSizes)
 		if err != nil {
 			return nil, xerrors.Errorf("add piece: %w", err)
 		}
diff --git a/utils.go b/utils.go
index 8fa887d3c..b235a8a83 100644
--- a/utils.go
+++ b/utils.go
@@ -1,7 +1,12 @@
 package sealing
 
 import (
+	"io"
 	"math/bits"
+	"math/rand"
+	"sync"
+
+	"github.com/hashicorp/go-multierror"
 
 	sectorbuilder "github.com/filecoin-project/go-sectorbuilder"
 )
@@ -42,6 +47,41 @@ func fillersFromRem(toFill uint64) ([]uint64, error) {
 	return out, nil
 }
 
+func (m *Sealing) fastPledgeCommitment(size uint64, parts uint64) (commP [sectorbuilder.CommLen]byte, err error) {
+	parts = 1 << bits.Len64(parts) // round down to nearest power of 2
+
+	piece := sectorbuilder.UserBytesForSectorSize(size / parts)
+	out := make([]sectorbuilder.PublicPieceInfo, parts)
+	var lk sync.Mutex
+
+	var wg sync.WaitGroup
+	wg.Add(int(parts))
+	for i := uint64(0); i < parts; i++ {
+		go func(i uint64) {
+			defer wg.Done()
+
+			commP, perr := sectorbuilder.GeneratePieceCommitment(io.LimitReader(rand.New(rand.NewSource(42+int64(i))), int64(piece)), piece)
+
+			lk.Lock()
+			if perr != nil {
+				err = multierror.Append(err, perr)
+			}
+			out[i] = sectorbuilder.PublicPieceInfo{
+				Size:  piece,
+				CommP: commP,
+			}
+			lk.Unlock()
+		}(i)
+	}
+	wg.Wait()
+
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	return sectorbuilder.GenerateDataCommitment(m.sb.SectorSize(), out)
+}
+
 func (m *Sealing) ListSectors() ([]SectorInfo, error) {
 	var sectors []SectorInfo
 	if err := m.sectors.List(&sectors); err != nil {
diff --git a/utils_test.go b/utils_test.go
index 02746a3d8..14d512a52 100644
--- a/utils_test.go
+++ b/utils_test.go
@@ -1,6 +1,7 @@
 package sealing
 
 import (
+	"github.com/filecoin-project/lotus/storage/sbmock"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -42,5 +43,13 @@ func TestFillersFromRem(t *testing.T) {
 		ub = sectorbuilder.UserBytesForSectorSize(uint64(9) << i)
 		testFill(t, ub, []uint64{ub1, ub4})
 	}
-
+}
+
+func TestFastPledge(t *testing.T) {
+	sz := uint64(16 << 20)
+
+	s := Sealing{sb: sbmock.NewMockSectorBuilder(0, sz)}
+	if _, err := s.fastPledgeCommitment(sz, 5); err != nil {
+		t.Fatalf("%+v", err)
+	}
 }