diff -Nuar a/vendor/magento/module-customer-import-export/Model/Import/Address.php b/vendor/magento/module-import-export/Model/Import/Address.php
--- a/vendor/magento/module-customer-import-export/Model/Import/Address.php
+++ b/vendor/magento/module-customer-import-export/Model/Import/Address.php
@@ -253,6 +253,11 @@ class Address extends AbstractCustomer
     private $optionsByWebsite = [];
 
     /**
+     * @var array
+     */
+    private $loadedAddresses;
+
+    /**
      * @param \Magento\Framework\Stdlib\StringUtils $string
      * @param \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig
      * @param \Magento\ImportExport\Model\ImportFactory $importFactory
@@ -443,20 +448,49 @@ class Address extends AbstractCustomer
      */
     protected function _initAddresses()
     {
-        /** @var $address \Magento\Customer\Model\Address */
-        foreach ($this->_addressCollection as $address) {
-            $customerId = $address->getParentId();
-            if (!isset($this->_addresses[$customerId])) {
-                $this->_addresses[$customerId] = [];
+        if ($this->_addressCollection->isLoaded()) {
+            /** @var $address \Magento\Customer\Model\Address */
+            foreach ($this->_addressCollection as $address) {
+                $customerId = $address->getParentId();
+                if (!isset($this->_addresses[$customerId])) {
+                    $this->_addresses[$customerId] = [];
+                }
+                $addressId = $address->getId();
+                if (!in_array($addressId, $this->_addresses[$customerId])) {
+                    $this->_addresses[$customerId][] = $addressId;
+                }
             }
-            $addressId = $address->getId();
-            if (!in_array($addressId, $this->_addresses[$customerId])) {
-                $this->_addresses[$customerId][] = $addressId;
+        } else {
+            foreach ($this->getLoadedAddresses() as $addressId => $address) {
+                $customerId = $address['parent_id'];
+                if (!isset($this->_addresses[$customerId])) {
+                    $this->_addresses[$customerId] = [];
+                }
+                if (!in_array($addressId, $this->_addresses[$customerId])) {
+                    $this->_addresses[$customerId][] = $addressId;
+                }
             }
         }
         return $this;
     }
 
+     /**
+     * @return array
+     */
+    private function getLoadedAddresses()
+    {
+        if (empty($this->loadedAddresses)) {
+            $collection = clone $this->_addressCollection;
+            $table = $collection->getMainTable();
+            $select = $collection->getSelect();
+            $select->reset('columns');
+            $select->reset('from');
+            $select->from($table, ['entity_id', 'parent_id']);
+            $this->loadedAddresses = $collection->getResource()->getConnection()->fetchAssoc($select);
+        }
+        return $this->loadedAddresses;
+    }
+
     /**
      * Initialize country regions hash for clever recognition
      *
diff -Nuar a/vendor/magento/module-customer-import-export/Model/ResourceModel/Import/Customer/Storage.php b/vendor/magento/module-customer-import-export/Model/ResourceModel/Import/Customer/Storage.php
--- a/vendor/magento/module-customer-import-export/Model/ResourceModel/Import/Customer/Storage.php
+++ b/vendor/magento/module-customer-import-export/Model/ResourceModel/Import/Customer/Storage.php
@@ -117,13 +117,18 @@ class Storage
      */
     public function getCustomerId($email, $websiteId)
     {
-        // lazy loading
-        $this->load();
+        if (!isset($this->_customerIds[$email][$websiteId])) {
+            $collection = clone $this->_customerCollection;
+            $mainTable = $collection->getResource()->getEntityTable();
 
-        if (isset($this->_customerIds[$email][$websiteId])) {
-            return $this->_customerIds[$email][$websiteId];
+            $select = $collection->getSelect();
+            $select->reset();
+            $select->from($mainTable, ['entity_id']);
+            $select->where($mainTable . '.email = ?', $email);
+            $select->where($mainTable . '.website_id = ?', $websiteId);
+            $this->_customerIds[$email][$websiteId] = $collection->getResource()->getConnection()->fetchOne($select);
         }
 
-        return false;
+        return $this->_customerIds[$email][$websiteId];
     }
 }