This page describes the change in more detail. Unfortunately they don't specify what "a lot" of memory is, but it was last updated in March 2003, so probably a gigabyte or two is plenty.

The best things you can do to maximize performance as far as pagefile goes is minimize use of it and latency accessing it. If possible, putting it on its own partition on an infrequently-accessed disk can give you a noticeable boost. Also, in the System control panel, you can set a minimum and maximum size. If you can afford the disk space you might want to just set both to several gigabytes, so that it never changes size, as this will be a performance hit and will cause fragmentation.

Of course probably the best way to improve performance is to get rid of resource-hogging crapware.

(And yeah, no real harm in trying out registry tweaks, as long as you back stuff up first and know how to deal with it if things go wrong.)

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