I'm working on a 10000 products Magento store. I scheduled a cronjob to run everyday at 7am to read a CSV file and update each product inventory and set it out of stock if new QTY is less than 1.

Currently, the update process takes around an hour (more/less) to update all 10000 products. My code as follow:

 $csv = new Varien_File_Csv();
 $csvData = $csv->getData('products.csv');

 foreach($csvData as $k => $v){
     // code to store product_id and new_qty into a temporary table 
 }

 $stock_item_model = Mage::getModel('cataloginventory/stock_item');
 $stock_item_collection = $stock_item_model->getCollection();

 foreach($stock_item_collection as $stock_item) {

     // load new_qty from temporary table based on product_id
     $new_qty = Mage::getResourceModel('custom/temp')->getQty($stock_item->getProductId())
     
     // set new QTY
     $stock_item->setQty($new_qty);
         
     // check if in stock or out of stock
     if($new_qty < 1) {
         $stock_item->setIsInStock(0);
     } else {
         $stock_item->setIsInStock(1);
     }   
 }

 // save all
 $stock_item_collection->walk('save'); // this takes around an hour to finish.

So, is there any other way to decrease the update time? Do I need to change the way I'm saving stock items?