diff --git a/CHANGES.md b/CHANGES.md
index 6d5c0fcb6..b11c3d7ac 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Dendrite 0.3.8 (2021-01-28)
+
+### Fixes
+
+* A well-known lookup regression in version 0.3.7 has been fixed
+
 ## Dendrite 0.3.7 (2021-01-26)
 
 ### Features
diff --git a/go.mod b/go.mod
index cbf3f597f..ff8291218 100644
--- a/go.mod
+++ b/go.mod
@@ -25,7 +25,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200518170932-783164aeeda4
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3
 	github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20210122154608-a38974bd8a37
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20210129163316-dd4d53729ead
 	github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91
 	github.com/matrix-org/pinecone v0.0.0-00010101000000-000000000000
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
diff --git a/go.sum b/go.sum
index 4e797a178..92dd0b821 100644
--- a/go.sum
+++ b/go.sum
@@ -579,8 +579,8 @@ github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26 h1:Hr3zjRsq2bh
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
 github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd h1:xVrqJK3xHREMNjwjljkAUaadalWc0rRbmVuQatzmgwg=
 github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20210122154608-a38974bd8a37 h1:si2CZZpwOLWZfDXfgHPkaTlaAkdJvpJzr1zVqyKXd0I=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20210122154608-a38974bd8a37/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20210129163316-dd4d53729ead h1:VmGJybKUQin8+NyA9ZkrHJpE8ygXzcON9peQH9LC92c=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20210129163316-dd4d53729ead/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91 h1:HJ6U3S3ljJqNffYMcIeAncp5qT/i+ZMiJ2JC2F0aXP4=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91/go.mod h1:sjyPyRxKM5uw1nD2cJ6O2OxI6GOqyVBfNXqKjBZTBZE=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7 h1:ntrLa/8xVzeSs8vHFHK25k0C+NV74sYMJnNSg5NoSRo=
diff --git a/internal/version.go b/internal/version.go
index 639fd3df0..f5c6a423f 100644
--- a/internal/version.go
+++ b/internal/version.go
@@ -17,7 +17,7 @@ var build string
 const (
 	VersionMajor = 0
 	VersionMinor = 3
-	VersionPatch = 7
+	VersionPatch = 8
 	VersionTag   = "" // example: "rc1"
 )
 
diff --git a/roomserver/internal/perform/perform_invite.go b/roomserver/internal/perform/perform_invite.go
index 085cb02ed..93a52350c 100644
--- a/roomserver/internal/perform/perform_invite.go
+++ b/roomserver/internal/perform/perform_invite.go
@@ -225,7 +225,7 @@ func buildInviteStrippedState(
 	for _, t := range []string{
 		gomatrixserverlib.MRoomName, gomatrixserverlib.MRoomCanonicalAlias,
 		gomatrixserverlib.MRoomAliases, gomatrixserverlib.MRoomJoinRules,
-		"m.room.avatar", "m.room.encryption",
+		"m.room.avatar", "m.room.encryption", gomatrixserverlib.MRoomCreate,
 	} {
 		stateWanted = append(stateWanted, gomatrixserverlib.StateKeyTuple{
 			EventType: t,
diff --git a/syncapi/streams/stream_devicelist.go b/syncapi/streams/stream_devicelist.go
index c43d50a49..9ea9d088f 100644
--- a/syncapi/streams/stream_devicelist.go
+++ b/syncapi/streams/stream_devicelist.go
@@ -19,7 +19,7 @@ func (p *DeviceListStreamProvider) CompleteSync(
 	ctx context.Context,
 	req *types.SyncRequest,
 ) types.LogPosition {
-	return p.IncrementalSync(ctx, req, types.LogPosition{}, p.LatestPosition(ctx))
+	return p.LatestPosition(ctx)
 }
 
 func (p *DeviceListStreamProvider) IncrementalSync(
diff --git a/syncapi/streams/stream_pdu.go b/syncapi/streams/stream_pdu.go
index d6d7ff444..ae38dc30e 100644
--- a/syncapi/streams/stream_pdu.go
+++ b/syncapi/streams/stream_pdu.go
@@ -2,18 +2,54 @@ package streams
 
 import (
 	"context"
+	"sync"
+	"time"
 
 	"github.com/matrix-org/dendrite/syncapi/types"
 	userapi "github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/gomatrixserverlib"
+	"go.uber.org/atomic"
 )
 
+// The max number of per-room goroutines to have running.
+// Too high and this will consume lots of CPU, too low and complete
+// sync responses will take longer to process.
+const PDU_STREAM_WORKERS = 256
+
+// The maximum number of tasks that can be queued in total before
+// backpressure will build up and the rests will start to block.
+const PDU_STREAM_QUEUESIZE = PDU_STREAM_WORKERS * 8
+
 type PDUStreamProvider struct {
 	StreamProvider
+
+	tasks   chan func()
+	workers atomic.Int32
+}
+
+func (p *PDUStreamProvider) worker() {
+	defer p.workers.Dec()
+	for {
+		select {
+		case f := <-p.tasks:
+			f()
+		case <-time.After(time.Second * 10):
+			return
+		}
+	}
+}
+
+func (p *PDUStreamProvider) queue(f func()) {
+	if p.workers.Load() < PDU_STREAM_WORKERS {
+		p.workers.Inc()
+		go p.worker()
+	}
+	p.tasks <- f
 }
 
 func (p *PDUStreamProvider) Setup() {
 	p.StreamProvider.Setup()
+	p.tasks = make(chan func(), PDU_STREAM_QUEUESIZE)
 
 	p.latestMutex.Lock()
 	defer p.latestMutex.Unlock()
@@ -52,19 +88,32 @@ func (p *PDUStreamProvider) CompleteSync(
 	eventFilter := req.Filter.Room.Timeline
 
 	// Build up a /sync response. Add joined rooms.
-	for _, roomID := range joinedRoomIDs {
-		var jr *types.JoinResponse
-		jr, err = p.getJoinResponseForCompleteSync(
-			ctx, roomID, r, &stateFilter, &eventFilter, req.Device,
-		)
-		if err != nil {
-			req.Log.WithError(err).Error("p.getJoinResponseForCompleteSync failed")
-			return from
-		}
-		req.Response.Rooms.Join[roomID] = *jr
-		req.Rooms[roomID] = gomatrixserverlib.Join
+	var reqMutex sync.Mutex
+	var reqWaitGroup sync.WaitGroup
+	reqWaitGroup.Add(len(joinedRoomIDs))
+	for _, room := range joinedRoomIDs {
+		roomID := room
+		p.queue(func() {
+			defer reqWaitGroup.Done()
+
+			var jr *types.JoinResponse
+			jr, err = p.getJoinResponseForCompleteSync(
+				ctx, roomID, r, &stateFilter, &eventFilter, req.Device,
+			)
+			if err != nil {
+				req.Log.WithError(err).Error("p.getJoinResponseForCompleteSync failed")
+				return
+			}
+
+			reqMutex.Lock()
+			defer reqMutex.Unlock()
+			req.Response.Rooms.Join[roomID] = *jr
+			req.Rooms[roomID] = gomatrixserverlib.Join
+		})
 	}
 
+	reqWaitGroup.Wait()
+
 	// Add peeked rooms.
 	peeks, err := p.DB.PeeksInRange(ctx, req.Device.UserID, req.Device.ID, r)
 	if err != nil {