Why is Fast Order Processing Crucial for New Online Shops?

I recently launched a small online boutique selling handcrafted pottery, but managing every transaction through direct social media messages is becoming incredibly slow. I spend my whole evening calculating shipping costs and sending bank details manually instead of designing new clay pots. I realize my business needs a professional store setup, so I am looking for the best ecommerce websites development company to build a secure automated checkout system. I need a platform that tracks my stock and prints invoices instantly. What features helped you automate your sales process when you started your shop?