My belief is that if you are doing eCommerce, then you owe it to your customers (existing and prospective) to offer your site with the best assurance of security, reliability, performance and trust.
This ALL starts with proper hosting, and your BEST course of action is to partner with a hosting company that understands eCommerce, and knows how to configure their systems to accommodate eCommerce platforms (such as Zencart).
Our little company has taken the decision to migrate ALL our client accounts to a UK-based host that specialises in eCommerce (and zencart), and it is proving to be a very good decision.
Performance is UP. (on many sites, page parse time has more than halved).
Reliability is UP.
Support is EXCELLENT (because they know ZC better than we do, they know how to advise on its configurations).
Knowing that we have top-rate hosting partners frees us up to do what we need to do... go our there and find more business!
Honestly... don't fool about with "cheap" hosting. In reality is is hugely costly in the long run - and may even cost you your business!