I have about 50.000 of records to import in a Magento store. What I have already tested: The file is about 50 MB.
Occasionally I've noticed bulk inserts that work by first creating a template model...
$blankProduct = Mage::getModel('catalog/product');
...then avoid the creation of the model for each record...
$newProduct = clone $blankProduct;
$newProduct->setIsMassupdate(true)
...
$newProduct->save();
It's slightly more efficient but probably not enough to get that massive import to a reasonable time.