Point of Sale Inventory application Development .net or PHP Whatever is more scaleable

Point of Sale Inventory application Development .net or PHP Whatever is more scaleable i have existing POS application based in PHP and mysql CodeIgniter framework application does not perform well when product is 100 thousand and 20 to 30 branch do transaction same time it get very slow even use dedicated server also so i need to recreate same application with strong technology and database work flow and everything clear i will guide each and every point all necessary module should be there there will be some extra feature will involve highly experience required should have all ERP module knowledge id if you only work with ERP application POS application if you have existing ERP and POS application full guide line of ERP module will not provide you should have knowledge of all module there is no fixed requirement freezing related to ERP all module should develop