I fully agree with the opinion that MAGENTO is to "heavy" and consumes too much CPU and memory. If you have your own dedicated server you may try MAGENTO.
But if you can afford shared hosting only use lightweight PRESTASHOP. Much shoppers do not need complicated functionalities provided by MAGENTO and therefore don't like it. More doesn't always mean better - sometimes simpler means better.
Moreover there is large set of PRESTASHOP extensions available free and commercial ones. so every shop owner may choose what he needs and wants. Every potential market gap is filled immediately e.g. if somebody noticed there is no fast checkout option in the guest mode buying. This kind of extension appears immediately on the market.
