Hi Heather,
I have experienced a lot of freezing on my very large projects over the years, but I have to say now that I don't really have that issue any more with those same projects. I have no idea why. Saving can be a problem and I often have to save to a new file name to save a very large project. I don't find the slide load time to be slow...in fact I am amazed at how quickly a slide loads in some of my projects which are sometimes running hundreds of lines of code. Are you talking about when previewing or when running a preview or when it has been published? Previewing the total project can take a very long time with very big projects - I tend to just try previewing a slide wherever possible (and it isn't always possible to do that of course).
re: Technical support...I have been one of the first to raise my frustrations with bugs etc...but I do find technical support to be very good. Some bugs still have not been fixed which is a frustration but that is more to do with priorities set beyond technical support. But I find when I raise a ticket I get a very rapid and detailed and supportive response from the technical team - always.
Chris