I use Paperform + Woocommerce to perform flash sales for a local bag store & we complete 111 orders within the first 5 minutes.
We all know that Woocommerce is not suitable for making flash sales. I have a nightmare when I work on the first flash sale for the same store. The site is down because it's like DDOS attack from all the customers that want to fight for limited packages.
I change the whole setup next year, using Paperform as front end layer to filter out the customers and release limited submission to fill. Once the user submits their detail through Paperform, Paperform will post the entry as a webhook and generate the invoice on Woocommerce end. User redirects to the Woocommerce payment page to complete the payment.
By this combination, I m able to make flash sales with a low budget and outstanding performance.