As someone that had to deal with Magento in production, it had serious scaling issues. I noticed more than 150 SQL queries to make a single purchase, with an ab

As someone that had to deal with Magento in production, it had serious scaling issues. I noticed more than 150 SQL queries to make a single purchase, with an abundance of lock contention issues... enough that they alone will bring a SQL server to its knees. It's great for selling one or two items per hour. If you are unfortunate enough to have a popular product, then your options with Magento may be limited. You can't easily shard a shopping cart. Once you max out at 48 cores and SSD RAID, you're stuck. Fortunately, for us, the problem resolved itself once we turned away enough customers.