Unable to Checkout with Large Number of Items (200+) in Shopping Cart - Magento 1.4.2

I've set up a B2B site powered by Magento 1.4.2 community edition. Occasionally, customers are trying to checkout with a large number of items in their shopping cart - up to 250! My issues are twofold:

1. When there are that many items in the cart, simple navigation through the site becomes extremely slow for the user.
2. On the OnePage checkout, when they get around to submitting the order, they get a javascript popup simply stating "undefined" and they remain on 开发者_运维问答the onepage checkout page.

Does anyone have any similar experience in dealing with this type of issue?

I've tried to implement memcached as well as full page caching hoping that it would help alleviate some of the stress off the server but it hasn't been effective in solving this issue.

I've ran into similar issues with the Enterprise version of Magento. You might try disabling the shopping cart sidebar, if you have not already done so, that should help the site speed when browsing. We changed the sidebar so that if there was more than 25 items in it, it would not try to load the products, which helped a great deal.

For the second error, if you use Firebug and Firefox as you step through the order process, you should get more error information than "undefined" which would help figure out what is going on there.

You could also try bumping up the memory_limit for php.ini, we ended up setting ours to 256mb, which solved most of the memory errors for our site.

I don't know the DB Structure of CE 1.4, but I had serious performance Issues with my CE 1.6.
Reason: Wrong and missing indexes. They where fixed in CE 1.6.2
You might check if it helps you.
I reduced the checkout time for 38 lines with 73 items total from 123 sec to 4 sec !!!!

Here it comes:

/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;

/* Foreign Keys must be dropped in the target to ensure that requires changes can be done*/

ALTER TABLE `core_url_rewrite` 
DROP FOREIGN KEY `FK_CORE_URL_REWRITE_CTGR_ID_CAT_CTGR_ENTT_ENTT_ID`  , 
DROP FOREIGN KEY `FK_CORE_URL_REWRITE_STORE_ID_CORE_STORE_STORE_ID`  ;


/* Alter table in target */
ALTER TABLE `catalog_category_entity_varchar` 
DROP KEY `MAGMI_CCEV_OPTIMIZATION_IDX` ;


/* Alter table in target */
ALTER TABLE `catalog_product_bundle_stock_index` 
DROP KEY `PRIMARY`, ADD PRIMARY KEY(`entity_id`,`website_id`,`stock_id`,`option_id`) ;


/* Alter table in target */
ALTER TABLE `catalog_product_entity_media_gallery` 
DROP KEY `MAGMI_CPEM_OPTIMIZATION_IDX` ;


/* Alter table in target */
ALTER TABLE `core_url_rewrite` 
CHANGE `id_path` `id_path` varchar(255)  COLLATE utf8_general_ci NULL COMMENT 'Id Path' after `store_id` , 
CHANGE `request_path` `request_path` varchar(255)  COLLATE utf8_general_ci NULL COMMENT 'Request Path' after `id_path` , 
CHANGE `target_path` `target_path` varchar(255)  COLLATE utf8_general_ci NULL COMMENT 'Target Path' after `request_path` , 
CHANGE `is_system` `is_system` smallint(5) unsigned   NULL DEFAULT 1 COMMENT 'Defines is Rewrite System' after `target_path` , 
CHANGE `options` `options` varchar(255)  COLLATE utf8_general_ci NULL COMMENT 'Options' after `is_system` , 
CHANGE `description` `description` varchar(255)  COLLATE utf8_general_ci NULL COMMENT 'Deascription' after `options` , 
CHANGE `category_id` `category_id` int(10) unsigned   NULL COMMENT 'Category Id' after `description` , 
CHANGE `product_id` `product_id` int(10) unsigned   NULL COMMENT 'Product Id' after `category_id` , 
ADD KEY `FK_CORE_URL_REWRITE_PRODUCT_ID_CATALOG_CATEGORY_ENTITY_ENTITY_ID`(`product_id`) , 
DROP KEY `FK_CORE_URL_REWRITE_PRODUCT_ID_CATALOG_PRODUCT_ENTITY_ENTITY_ID` , 
ADD CONSTRAINT `FK_CORE_URL_REWRITE_PRODUCT_ID_CATALOG_CATEGORY_ENTITY_ENTITY_ID` 
FOREIGN KEY (`product_id`) REFERENCES `catalog_product_entity` (`entity_id`) ON DELETE CASCADE ON UPDATE CASCADE , 
DROP FOREIGN KEY `FK_CORE_URL_REWRITE_PRODUCT_ID_CATALOG_PRODUCT_ENTITY_ENTITY_ID`  ;


/* Alter table in target */
ALTER TABLE `eav_attribute` 
DROP KEY `MAGMI_EA_CODE_OPTIMIZATION_IDX` ;


/* Alter table in target */
ALTER TABLE `eav_attribute_option_value` 
DROP KEY `MAGMI_EAOV_OPTIMIZATION_IDX` ;


/* The foreign keys that were dropped are now re-created*/

ALTER TABLE `core_url_rewrite` 
ADD CONSTRAINT `FK_CORE_URL_REWRITE_CTGR_ID_CAT_CTGR_ENTT_ENTT_ID` 
FOREIGN KEY (`category_id`) REFERENCES `catalog_category_entity` (`entity_id`) ON DELETE CASCADE ON UPDATE CASCADE , 
ADD CONSTRAINT `FK_CORE_URL_REWRITE_STORE_ID_CORE_STORE_STORE_ID` 
FOREIGN KEY (`store_id`) REFERENCES `core_store` (`store_id`) ON DELETE CASCADE ON UPDATE CASCADE ;

/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;