From 41ad2be4340d7b18a4669aa9becef8936597f000 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C5=91rinc?= <pap.lorinc@gmail.com>
Date: Sun, 29 Jun 2025 20:20:17 +0200
Subject: [PATCH 1/2] mempool: Avoid expensive loop in `removeForBlock` during
 IBD

During Initial Block Download, the mempool is usually empty, but `CTxMemPool::removeForBlock` is still called for every connected block where we:
* iterate over every transaction in the block even though none will be found in the empty `mapTx`, always leaving `txs_removed_for_block` empty...
* which is pre-allocated regardless with 40 bytes * vtx.size(), even though it will always remain empty.

This change introduces a minor performance optimization by only executing the loop if any of the core mempool maps have any contents.

The call to `MempoolTransactionsRemovedForBlock` and the updates to the rolling fee logic remain unchanged.

The `removeForBlock` was also updated stylistically to match the surrounding methods and a clarification was added to clarify that it affects fee estimation as well.
---
 src/txmempool.cpp | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index d65005fc645..7a66751db5a 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -661,26 +661,25 @@ void CTxMemPool::removeConflicts(const CTransaction &tx)
     }
 }
 
-/**
- * Called when a block is connected. Removes from mempool.
- */
 void CTxMemPool::removeForBlock(const std::vector<CTransactionRef>& vtx, unsigned int nBlockHeight)
 {
+    // Remove confirmed txs and conflicts when a new block is connected, updating the fee logic
     AssertLockHeld(cs);
     Assume(!m_have_changeset);
     std::vector<RemovedMempoolTransactionInfo> txs_removed_for_block;
-    txs_removed_for_block.reserve(vtx.size());
-    for (const auto& tx : vtx)
-    {
-        txiter it = mapTx.find(tx->GetHash());
-        if (it != mapTx.end()) {
-            setEntries stage;
-            stage.insert(it);
-            txs_removed_for_block.emplace_back(*it);
-            RemoveStaged(stage, true, MemPoolRemovalReason::BLOCK);
+    if (mapTx.size() || mapNextTx.size() || mapDeltas.size()) {
+        txs_removed_for_block.reserve(vtx.size());
+        for (const auto& tx : vtx) {
+            txiter it = mapTx.find(tx->GetHash());
+            if (it != mapTx.end()) {
+                setEntries stage;
+                stage.insert(it);
+                txs_removed_for_block.emplace_back(*it);
+                RemoveStaged(stage, true, MemPoolRemovalReason::BLOCK);
+            }
+            removeConflicts(*tx);
+            ClearPrioritisation(tx->GetHash());
         }
-        removeConflicts(*tx);
-        ClearPrioritisation(tx->GetHash());
     }
     if (m_opts.signals) {
         m_opts.signals->MempoolTransactionsRemovedForBlock(txs_removed_for_block, nBlockHeight);

From 249889bee6b88eb9814eb969e6fb108f86a4bf98 Mon Sep 17 00:00:00 2001
From: furszy <matiasfurszyfer@protonmail.com>
Date: Wed, 11 Jun 2025 10:19:19 -0400
Subject: [PATCH 2/2] orphanage: avoid vtx iteration when no orphans

---
 src/node/txorphanage.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/node/txorphanage.cpp b/src/node/txorphanage.cpp
index 6093be46ce4..ce087d17ffb 100644
--- a/src/node/txorphanage.cpp
+++ b/src/node/txorphanage.cpp
@@ -567,6 +567,8 @@ bool TxOrphanageImpl::HaveTxToReconsider(NodeId peer)
 }
 void TxOrphanageImpl::EraseForBlock(const CBlock& block)
 {
+    if (m_orphans.empty()) return;
+
     std::set<Wtxid> wtxids_to_erase;
     for (const CTransactionRef& ptx : block.vtx) {
         const CTransaction& block_tx = *ptx;