First of all, I will never compare my script to a top-rated competitor company yet as I am doing a solo development here as a solo developer. But what I do I make sure to do it in terms of quality and perfection.
But remember this, you are using a $450 script to do a bulk scan, instead of paying $50 to $100 for a 10,000 to 50,000 email address scan. In that case, Email Verifier Pro is still profitable for you.
Though regarding the fast and slowness a possible answer to this, they do scan target server location first and use proxy to one of their co-located servers to that location for speeding up the process. This type of rich feature has not been implemented yet within our script. As a solo developer, I am working on this script improvement as quickly as I can and applying new updates as necessary. You can find its road map here. Also, I do welcome any suggestions from users related to any features.