diff --git a/lib/dns/qp.c b/lib/dns/qp.c
index 3805845b91..79a0b8e6ee 100644
--- a/lib/dns/qp.c
+++ b/lib/dns/qp.c
@@ -1785,10 +1785,14 @@ dns_qpchain_init(dns_qpreadable_t qpr, dns_qpchain_t *chain) {
 	REQUIRE(QP_VALID(qp));
 	REQUIRE(chain != NULL);
 
-	*chain = (dns_qpchain_t){
-		.magic = QPCHAIN_MAGIC,
-		.qp = qp,
-	};
+	/*
+	 * dns_qpchain_t contains a 2kb buffer, which is slow to
+	 * zero-initialize. Therefore we avoid designated initializers, and
+	 * initialize each field manually.
+	 */
+	chain->magic = QPCHAIN_MAGIC;
+	chain->qp = qp;
+	chain->len = 0;
 }
 
 unsigned int
@@ -1821,10 +1825,19 @@ dns_qpiter_init(dns_qpreadable_t qpr, dns_qpiter_t *qpi) {
 	dns_qpreader_t *qp = dns_qpreader(qpr);
 	REQUIRE(QP_VALID(qp));
 	REQUIRE(qpi != NULL);
-	*qpi = (dns_qpiter_t){
-		.qp = qp,
-		.magic = QPITER_MAGIC,
-	};
+
+	/*
+	 * dns_qpiter_t contains a 4kb buffer, which is slow to zero-initialize.
+	 * Therefore we avoid designated initializers, and initialize each
+	 * field manually.
+	 */
+	qpi->qp = qp;
+	qpi->sp = 0;
+	qpi->magic = QPITER_MAGIC;
+	/*
+	 * The top of the stack must be initialized.
+	 */
+	qpi->stack[qpi->sp] = NULL;
 }
 
 /*
diff --git a/lib/dns/qpcache.c b/lib/dns/qpcache.c
index 1b50608203..3b7f5680b1 100644
--- a/lib/dns/qpcache.c
+++ b/lib/dns/qpcache.c
@@ -1458,6 +1458,29 @@ find_coveringnsec(qpc_search_t *search, const dns_name_t *name,
 	 (DNS_TRUST_PENDING((found)->trust) &&             \
 	  (((options) & DNS_DBFIND_PENDINGOK) == 0)))
 
+static void
+qpc_search_init(qpc_search_t *search, qpcache_t *db, unsigned int options,
+		isc_stdtime_t now) {
+	/*
+	 * qpc_search_t contains two structures with large buffers (dns_qpiter_t
+	 * and dns_qpchain_t). Those two structures will be initialized later by
+	 * dns_qp_lookup anyway.
+	 * To avoid the overhead of zero initialization, we avoid designated
+	 * initializers and initialize all "small" fields manually.
+	 */
+	search->qpdb = (qpcache_t *)db;
+	search->options = options;
+	/*
+	 * qpch->in - Init by dns_qp_lookup
+	 * qpiter - Init by dns_qp_lookup
+	 */
+	search->need_cleanup = false;
+	search->now = now ? now : isc_stdtime_now();
+	search->zonecut = NULL;
+	search->zonecut_header = NULL;
+	search->zonecut_sigheader = NULL;
+}
+
 static isc_result_t
 qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 	     dns_rdatatype_t type, unsigned int options, isc_stdtime_t __now,
@@ -1479,11 +1502,9 @@ qpcache_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 	dns_slabheader_t *foundsig = NULL, *nssig = NULL, *cnamesig = NULL;
 	dns_slabheader_t *nsecheader = NULL, *nsecsig = NULL;
 	dns_typepair_t sigtype, negtype;
-	qpc_search_t search = (qpc_search_t){
-		.qpdb = (qpcache_t *)db,
-		.options = options,
-		.now = __now ? __now : isc_stdtime_now(),
-	};
+
+	qpc_search_t search;
+	qpc_search_init(&search, (qpcache_t *)db, options, __now);
 
 	REQUIRE(VALID_QPDB((qpcache_t *)db));
 	REQUIRE(version == NULL);
diff --git a/lib/dns/qpzone.c b/lib/dns/qpzone.c
index 9ede2dfa4c..4c60d4c17d 100644
--- a/lib/dns/qpzone.c
+++ b/lib/dns/qpzone.c
@@ -3326,6 +3326,34 @@ qpzone_check_zonecut(qpznode_t *node, void *arg DNS__DB_FLARG) {
 	return result;
 }
 
+static void
+qpz_search_init(qpz_search_t *search, qpzonedb_t *db, qpz_version_t *version,
+		unsigned int options) {
+	/*
+	 * qpz_search_t contains two structures with large buffers (dns_qpiter_t
+	 * and dns_qpchain_t). Those two structures will be initialized later by
+	 * dns_qp_lookup anyway.
+	 * To avoid the overhead of zero initialization, we avoid designated
+	 * initializers and initialize all "small" fields manually.
+	 */
+	search->qpdb = db;
+	search->version = version;
+	search->qpr = (dns_qpread_t){};
+	search->serial = version->serial;
+	search->options = options;
+	/*
+	 * qpch->in -- init in dns_qp_lookup
+	 * qpiter -- init in dns_qp_lookup
+	 */
+	search->copy_name = false;
+	search->need_cleanup = false;
+	search->wild = false;
+	search->zonecut = NULL;
+	search->zonecut_header = NULL;
+	search->zonecut_sigheader = NULL;
+	dns_fixedname_init(&search->zonecut_name);
+}
+
 static isc_result_t
 qpzone_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 	    dns_rdatatype_t type, unsigned int options,
@@ -3335,7 +3363,6 @@ qpzone_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 	isc_result_t result;
 	qpzonedb_t *qpdb = (qpzonedb_t *)db;
 	qpznode_t *node = NULL;
-	qpz_search_t search;
 	bool cname_ok = true, close_version = false;
 	bool maybe_zonecut = false, at_zonecut = false;
 	bool wild = false, empty_node = false;
@@ -3361,13 +3388,9 @@ qpzone_find(dns_db_t *db, const dns_name_t *name, dns_dbversion_t *version,
 		close_version = true;
 	}
 
-	search = (qpz_search_t){
-		.qpdb = (qpzonedb_t *)db,
-		.version = (qpz_version_t *)version,
-		.serial = ((qpz_version_t *)version)->serial,
-		.options = options,
-	};
-	dns_fixedname_init(&search.zonecut_name);
+	qpz_search_t search;
+	qpz_search_init(&search, (qpzonedb_t *)db, (qpz_version_t *)version,
+			options);
 
 	if ((options & DNS_DBFIND_FORCENSEC3) != 0) {
 		dns_qpmulti_query(qpdb->nsec3, &search.qpr);