I don’t think there are that many flaws and disadvantages of using the default WordPress commenting system, many web-masters still rely upon it, and aren’t thinking about alternatives just yet. Though, those who’re more conscious of how Google ranks pages, might want to reconsider!
The speed at which your blog loads is critical to attracting more readers to your blog. If your blog takes a long time to load, many readers may leave your blog before they have the chance to read it. Being the internet-savvy person that I am, I’ll settle for slow sites in various occasions, but as soon as it starts to happen all the time – I raise my concern.