I just switched to a new host. I changed to this host because my site was consistently slow on my old host. Things are about 80% better with my new host, but I still have problems with my site being slow now and then.
I am on a shared server. I've noticed that sometimes the exact same page will take anywhere between 1-15 seconds to load... No verifiable problems with my ISP or with their server (besides being on a shared server). I first noticed this problem when just using my site, and then I verified the times with http://www.numion.com/Stopwatch/index.html.
I asked them about this and they said everything is fine with my site and with the server. I am not getting very high traffic right now. I suspect because the site is slow sometimes for some people...
They suggested I change from a shared plan to a Virtual Private Server (VPS) plan. My question is: will this really improve my loads times or will it just take away from my bottom line?
In my experience indeed VPS server will perform much better (and consistent) than shared hosting. However you need to be carefully to chose the right virtualisation technology, the one which will give you exclusive usage of resources (CPU and RAM) allocated to your Virtual machine. For example Xen Visualisation does that.