Unfortunately, Zets, upon further testing, we believe that its not the amount of memory that we're using that causes things to get thrown in the Page File and cause long loads, but it's actually the number of requests for memory that the Unreal Engine makes. We believe we have crossed some threshold in Windows Vista and Windows 7(probably 65536 requests). This is an Unreal Engine problem in the way it functions at its core, which we may not be able to simply fix without rewriting the engine. Normally, any application looking to utilize a large chunk of memory would combine all similar requests into a single request in order to improve performance, which is probably how it's done in more modern engines. With this type of intelligent single request system, on top of being faster itself, it also never maxes out the number of requests allowed before the Operating System says "Enough! Use the Page File for future requests!"
This is our current understanding of what's happening, but we are continuing to look into any possible fixes that we may implement ourselves to resolve this issue.