Performance and Miva. Dedicated server worth it? Other options?

I've been selling clothing for a number of years at conventions. Recently I've started trying to implement an online store. It is not live yet, but already the performance is very slow (it varies depending on the time of day).

For a number of years I've had several basic HTML pages and email hosted by Valueweb/Hostway. I got my account through Costco, and it is $15 per month. I've been happy with their services up until now.

My Costco account includes a free shopping cart, Miva 4.23. It is on a shared server via Hostway. Last week I've started configuring it, but both the admin screens and the storefront have been slow. In addition, I purchased the OpenUI and an Inventory Module from Viking Coders (about $189). The reason for the inventory module is to track inventory at the options level (i.e. colors, sizes), and prevent the sale of items if they are out of stock (by color, and size). I installed these last week, and now both the admin panel and the storefront are even slower.

Here is a link to my storefront (the store is not linked to my homepage and I haven't gone "live" yet, and it has a ways to go):
Bodkini?

If you go there and navigate around, does it seem slow to you?

I called tech support at Hostway, and they said they could not do anything, and that moving me to another shared server wouldn't help. They also partially blamed me installing OpenUI, and that this is causing the slowness, at least in part. I said that I'm sure many other Miva users use it, and asked that shouldn't I expect that their servers be able to perform with it, and he didn't answer the question except maybe to uninstall OpenUI (however I need it, in order to track the inventory in the way I want to). He said the only other thing might be to get a dedicated server.

They transferred me to sales, and they quoted me $99 per month for a basic dedicated server, and I would have to buy my own Miva license, which is about $500. Apparently the free license offered through Costco is just for the shared server license.

So, I need to make a decision. The first is to continue with my current route, and hope that the online store isn't too annoyingly slow. The second is maybe to try a different hosting company and perhaps a different shopping cart (such as Cubecart). I've been reading the various threads in this forum and learning what I can about this option. The third is to go with a fully dedicated server, either via Hostway or another host, and buy either Miva or a different shopping cart. My concern is the cost, plus the admin time required to maintain a dedicated server, and the technical knowledge required to move my files and get everything configured.

After reading some of the various threads, I am thinking about switching to a host such as lunarpages, buying Cubecart (or maybe using the free one), and following the reasonable budget Rodney suggested in one of his other posts (I can't find it now). From what I've read I expect Cubecart (or zencart or some of the others positively discussed in this forum) would serve better and be more cost effective than a new $500 Miva cart.

However I'm also upset with Hostway. It seems reasonable to expect decent performance, especially if they offer a 'free' shopping cart.

The good news is, I'm not live yet.

If you were me, what might you do at this juncture?

As for dedicated servers, are they worth the cost and time commitment to maintain them? For me, I feel it is overkill, as I am just getting my online store going and won't have a lot of customers for awhile. However I'm curious about this concept.

Thank you for taking the time to read my situation, and offering ideas and suggestions.

Mark.