There are quite a few threads, wiki pages and groups describing different ways to speed up Magento. The trouble is, with a shared hosting environment like servage you’re pretty limited as to what you can do. Things you’d normally try are:
* Optimising MySQL/InnoDB configuration
* Switching KeepAlives on in Apache
* Installing an opcode cache like APC
* Moving your cached directory into a tmpfs (in-memory filesystem)
I’m sure there are other ways too, and more being discovered all the time.
If you’re serious about hosting a Magento store you might want to look for a web host who offers VPS or dedicated servers and understands the performance challenges Magento site owners face. Varien have partnerships with some, and some are active on these forums. The more hassle you can offload to your webhost the better :o)
If you’re new to PHP you’re probably looking at one of the most complex, but also one of the best-written PHP applications around. It’ll be a tough challenge to learn, but you’ll be glad when you’ve done it.
Having said that the way Magento is written and supported you’ve got a whole community of people working alongside you, so there’ll always be someone to help out.