Endlos list of carts will be created

-- HikaShop version -- : 3.1.1 Business
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.0.17
-- Browser(s) name and version -- : mozilla & safaria (latest version)
-- Error-message(debug-mod must be tuned on) -- : Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 20480 bytes) in /homepages/25/d83827768/htdocs/2rs/administrator/components/com_hikashop/classes/cart.php on line 2718

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 20480 bytes) in /homepages/25/d83827768/htdocs/2rs/libraries/vendor/joomla/registry/src/Registry.php on line 85

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 835584 bytes) in Unknown on line 0

Hi,

I've an endless list cart entries in the shop backend. By our the traffic this cannot be the realistic Checkout process etc works fine and we have correct orders. So system is working.
But I don't any idea where these carts come from. From a timing it could be that every product view creates an entry. After testing the cart overview in the backend creates now :

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 20480 bytes) in /homepages/25/d83827768/htdocs/2rs/administrator/components/com_hikashop/classes/cart.php on line 2718

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 20480 bytes) in /homepages/25/d83827768/htdocs/2rs/libraries/vendor/joomla/registry/src/Registry.php on line 85

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 835584 bytes) in Unknown on line 0