requesting.go | 14 ++++++++------
 torrent.go    |  5 +++++

diff --git a/requesting.go b/requesting.go
index 3c204b843cb5e6ec0431e219f01076874243079e..98e9e88bf34048a6ae8ec6ddaaaefd49c8a9dc02 100644
--- a/requesting.go
+++ b/requesting.go
@@ -70,7 +70,7 @@
 type desiredPeerRequests struct {
 	requestIndexes []RequestIndex
 	peer           *Peer
-	pieceStates    map[pieceIndex]request_strategy.PieceRequestOrderState
+	pieceStates    []request_strategy.PieceRequestOrderState
 }
 
 func (p *desiredPeerRequests) Len() int {
@@ -95,8 +95,8 @@ 			!p.peer.peerAllowedFast.Contains(leftPieceIndex),
 			!p.peer.peerAllowedFast.Contains(rightPieceIndex),
 		)
 	}
-	leftPiece := p.pieceStates[leftPieceIndex]
-	rightPiece := p.pieceStates[rightPieceIndex]
+	leftPiece := &p.pieceStates[leftPieceIndex]
+	rightPiece := &p.pieceStates[rightPieceIndex]
 	// Putting this first means we can steal requests from lesser-performing peers for our first few
 	// new requests.
 	priority := func() piecePriority {
@@ -193,8 +193,9 @@ 		return
 	}
 	input := t.getRequestStrategyInput()
 	requestHeap := desiredPeerRequests{
-		peer:        p,
-		pieceStates: make(map[pieceIndex]request_strategy.PieceRequestOrderState),
+		peer:           p,
+		pieceStates:    t.requestPieceStates,
+		requestIndexes: t.requestIndexes,
 	}
 	request_strategy.GetRequestablePieces(
 		input,
@@ -206,6 +207,7 @@ 			}
 			if !p.peerHasPiece(pieceIndex) {
 				return
 			}
+			requestHeap.pieceStates[pieceIndex] = pieceExtra
 			allowedFast := p.peerAllowedFast.Contains(pieceIndex)
 			p.t.piece(pieceIndex).undirtiedChunksIter.Iter(func(ci request_strategy.ChunkIndex) {
 				r := p.t.pieceRequestIndexOffset(pieceIndex) + ci
@@ -228,7 +230,6 @@ 					// Can't re-request while awaiting acknowledgement.
 					return
 				}
 				requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
-				requestHeap.pieceStates[pieceIndex] = pieceExtra
 			})
 		},
 	)
@@ -256,6 +257,7 @@ 		pprof.Labels("update request", p.needRequestUpdate),
 		func(_ context.Context) {
 			next := p.getDesiredRequestState()
 			p.applyRequestState(next)
+			p.t.requestIndexes = next.Requests.requestIndexes[:0]
 		},
 	)
 }
diff --git a/torrent.go b/torrent.go
index 4f06d6501a9c02e3662e8b36ac665317a696ecfc..dbfbea18ef2a5d8998bd283605724e5eefd325e6 100644
--- a/torrent.go
+++ b/torrent.go
@@ -157,6 +157,10 @@ 	activeSources sync.Map
 	sourcesLogger log.Logger
 
 	smartBanCache smartBanCache
+
+	// Large allocations reused between request state updates.
+	requestPieceStates []request_strategy.PieceRequestOrderState
+	requestIndexes     []RequestIndex
 }
 
 func (t *Torrent) selectivePieceAvailabilityFromPeers(i pieceIndex) (count int) {
@@ -457,6 +461,7 @@ // This seems to be all the follow-up tasks after info is set, that can't fail.
 func (t *Torrent) onSetInfo() {
 	t.initPieceRequestOrder()
 	MakeSliceWithLength(&t.requestState, t.numChunks())
+	MakeSliceWithLength(&t.requestPieceStates, t.numPieces())
 	for i := range t.pieces {
 		p := &t.pieces[i]
 		// Need to add relativeAvailability before updating piece completion, as that may result in conns