diff --git a/blocklocator.go b/blocklocator.go
index 5ae9d5e2..a3258f25 100644
--- a/blocklocator.go
+++ b/blocklocator.go
@@ -29,7 +29,8 @@ type BlockLocator []*btcwire.ShaHash
 //    consist of the passed hash
 func (b *BlockChain) BlockLocatorFromHash(hash *btcwire.ShaHash) BlockLocator {
 	// The locator contains the requested hash at the very least.
-	locator := BlockLocator([]*btcwire.ShaHash{hash})
+	locator := make(BlockLocator, 0, btcwire.MaxBlockLocatorsPerMsg)
+	locator = append(locator, hash)
 
 	// Nothing more to do if a locator for the genesis hash was requested.
 	if hash.IsEqual(b.chainParams().GenesisHash) {
diff --git a/process.go b/process.go
index 98e120f4..60894d68 100644
--- a/process.go
+++ b/process.go
@@ -38,10 +38,15 @@ func (b *BlockChain) blockExists(hash *btcwire.ShaHash) bool {
 // It repeats the process for the newly accepted blocks (to detect further
 // orphans which may no longer be orphans) until there are no more.
 func (b *BlockChain) processOrphans(hash *btcwire.ShaHash) error {
-	processHashes := []*btcwire.ShaHash{hash}
+	// Start with processing at least the passed hash.  Leave a little room
+	// for additional orphan blocks that need to be processed without
+	// needing to grow the array in the common case.
+	processHashes := make([]*btcwire.ShaHash, 0, 10)
+	processHashes = append(processHashes, hash)
 	for len(processHashes) > 0 {
 		// Pop the first hash to process from the slice.
 		processHash := processHashes[0]
+		processHashes[0] = nil // Prevent GC leak.
 		processHashes = processHashes[1:]
 
 		// Look up all orphans that are parented by the block we just
diff --git a/txlookup.go b/txlookup.go
index 50f5c184..0cc08a88 100644
--- a/txlookup.go
+++ b/txlookup.go
@@ -215,10 +215,20 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 		txInFlight[*txHash] = i
 	}
 
+	// Make a reasonable guess for the maximum number of needed input
+	// transactions to use as the starting point for the needed transactions
+	// array.  The array will dynamically grow as needed, but it's much less
+	// overhead to avoid growing and copying the array multiple times in the
+	// common case.  Each block usually has no more than ten inputs per
+	// transaction, so use that as a reasonable starting point.  A block
+	// with 2,000 transactions would only result in around 156KB on a 64-bit
+	// system using this approach.
+	maxNeededHint := (len(transactions) - 1) * 10
+	txNeededList := make([]*btcwire.ShaHash, 0, maxNeededHint)
+
 	// Loop through all of the transaction inputs (except for the coinbase
 	// which has no inputs) collecting them into lists of what is needed and
 	// what is already known (in-flight).
-	var txNeededList []*btcwire.ShaHash
 	txStore := make(map[btcwire.ShaHash]*txData)
 	for i, tx := range transactions[1:] {
 		for _, txIn := range tx.TxIn {