diff --git a/src/bench/rpc_blockchain.cpp b/src/bench/rpc_blockchain.cpp
index df951a14e49..52916242fa5 100644
--- a/src/bench/rpc_blockchain.cpp
+++ b/src/bench/rpc_blockchain.cpp
@@ -45,17 +45,34 @@ struct TestBlockAndIndex {
 
 } // namespace
 
-static void BlockToJsonVerbose(benchmark::Bench& bench)
+static void BlockToJson(benchmark::Bench& bench, TxVerbosity verbosity)
 {
     TestBlockAndIndex data;
     const uint256 pow_limit{data.testing_setup->m_node.chainman->GetParams().GetConsensus().powLimit};
     bench.run([&] {
-        auto univalue = blockToJSON(data.testing_setup->m_node.chainman->m_blockman, data.block, data.blockindex, data.blockindex, TxVerbosity::SHOW_DETAILS_AND_PREVOUT, pow_limit);
+        auto univalue = blockToJSON(data.testing_setup->m_node.chainman->m_blockman, data.block, data.blockindex, data.blockindex, verbosity, pow_limit);
         ankerl::nanobench::doNotOptimizeAway(univalue);
     });
 }
 
-BENCHMARK(BlockToJsonVerbose, benchmark::PriorityLevel::HIGH);
+static void BlockToJsonVerbosity1(benchmark::Bench& bench)
+{
+    BlockToJson(bench, TxVerbosity::SHOW_TXID);
+}
+
+static void BlockToJsonVerbosity2(benchmark::Bench& bench)
+{
+    BlockToJson(bench, TxVerbosity::SHOW_DETAILS);
+}
+
+static void BlockToJsonVerbosity3(benchmark::Bench& bench)
+{
+    BlockToJson(bench, TxVerbosity::SHOW_DETAILS_AND_PREVOUT);
+}
+
+BENCHMARK(BlockToJsonVerbosity1, benchmark::PriorityLevel::HIGH);
+BENCHMARK(BlockToJsonVerbosity2, benchmark::PriorityLevel::HIGH);
+BENCHMARK(BlockToJsonVerbosity3, benchmark::PriorityLevel::HIGH);
 
 static void BlockToJsonVerboseWrite(benchmark::Bench& bench)
 {
diff --git a/src/core_write.cpp b/src/core_write.cpp
index 253dfde1006..14836f51489 100644
--- a/src/core_write.cpp
+++ b/src/core_write.cpp
@@ -181,6 +181,7 @@ void TxToUniv(const CTransaction& tx, const uint256& block_hash, UniValue& entry
     entry.pushKV("locktime", (int64_t)tx.nLockTime);
 
     UniValue vin{UniValue::VARR};
+    vin.reserve(tx.vin.size());
 
     // If available, use Undo data to calculate the fee. Note that txundo == nullptr
     // for coinbase transactions and for transactions where undo data is unavailable.
@@ -203,6 +204,7 @@ void TxToUniv(const CTransaction& tx, const uint256& block_hash, UniValue& entry
         }
         if (!tx.vin[i].scriptWitness.IsNull()) {
             UniValue txinwitness(UniValue::VARR);
+            txinwitness.reserve(tx.vin[i].scriptWitness.stack.size());
             for (const auto& item : tx.vin[i].scriptWitness.stack) {
                 txinwitness.push_back(HexStr(item));
             }
@@ -232,6 +234,7 @@ void TxToUniv(const CTransaction& tx, const uint256& block_hash, UniValue& entry
     entry.pushKV("vin", std::move(vin));
 
     UniValue vout(UniValue::VARR);
+    vout.reserve(tx.vout.size());
     for (unsigned int i = 0; i < tx.vout.size(); i++) {
         const CTxOut& txout = tx.vout[i];
 
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index ac1ce6285f7..0ac36b005ec 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -184,6 +184,7 @@ UniValue blockToJSON(BlockManager& blockman, const CBlock& block, const CBlockIn
     result.pushKV("size", (int)::GetSerializeSize(TX_WITH_WITNESS(block)));
     result.pushKV("weight", (int)::GetBlockWeight(block));
     UniValue txs(UniValue::VARR);
+    txs.reserve(block.vtx.size());
 
     switch (verbosity) {
         case TxVerbosity::SHOW_TXID:
diff --git a/src/univalue/include/univalue.h b/src/univalue/include/univalue.h
index 19a500d191a..bc71677bab6 100644
--- a/src/univalue/include/univalue.h
+++ b/src/univalue/include/univalue.h
@@ -70,6 +70,8 @@ public:
 
     size_t size() const { return values.size(); }
 
+    void reserve(size_t new_cap);
+
     void getObjMap(std::map<std::string,UniValue>& kv) const;
     bool checkObject(const std::map<std::string,UniValue::VType>& memberTypes) const;
     const UniValue& operator[](const std::string& key) const;
diff --git a/src/univalue/lib/univalue.cpp b/src/univalue/lib/univalue.cpp
index 656d2e82030..4d37c81fe87 100644
--- a/src/univalue/lib/univalue.cpp
+++ b/src/univalue/lib/univalue.cpp
@@ -240,3 +240,10 @@ const UniValue& UniValue::find_value(std::string_view key) const
     return NullUniValue;
 }
 
+void UniValue::reserve(size_t new_cap)
+{
+    values.reserve(new_cap);
+    if (typ == VOBJ) {
+        keys.reserve(new_cap);
+    }
+}