Looking for some performance tips

[HGeneAnthony]

I develop on the desktop for the most part.  I've made dynamic sites before but on rare occassions.  The thing is the two worlds are very different.  With a desktop app you typically have one or a few users using an app at a time and almost all the processing is done on the client end.  With a web site you have multiple connections to a server and you have to worry about the end user pulling data down especially with dial-up users and resource depletion.  I'm typically torn with which way to go with my sites.  For example, I tend to like to use classes heavily to manage data.  On the desktop modular design is important and the classes should do what they need to do and nothing else, handle their data accordingly, and create methods to work with data.  This is important when writing any app of any real complexity however even though it seems to be similar on the web it's not always.  For example, if I was going to pull data from my database I would typically throw it into a collection of some sort (rather than displaying it outright) and I would create functions to access it.  This way the class is only responsible for the data, it doesn't work with the form, it makes it easier to manage the data if I change things later, it keeps things clean, etc.  However, with a site I don't know how bad holding the data could be on the server.  It creates cleaner code but it could be heavier on resources since the servers creating variables to hold data rather than just shooting it out.  So how should I handle the data, shoot out at once or hold.