Well, first I guess I must say it would cost you a bit of money which might be a red flag right from the start depending on your financial situation, it should be around 8 bucks for CoreAVC and about 30 for WinAvi, though you can download trial versions from both programs I believe.
Installing CoreAVC and specifying its use in WinAvi along with pretty much every other media player or converter should speed up the decoding process dramatically which is perfect for watching those high quality fansubs or in your case, to decode the h264 files and re-encode to mpeg2 which is where WinAvi comes in. Now, many people frown upon WinAvi saying it is inferior to other popular Dvd encoders like XtoDVD but as far as speed is concerned no other program can compare and that's what you want.
So to summarize,
CoreAvc plus
WinAvi Video Converter should give you faster h264 decoding speeds and might speed up your dvd making, though yes, WinAvi lacks a lack of the costumization you might be used to in your dvds (menus, multiple audio streams) but it's something you might check out as an alternative, I hear CoreAvc does wonders for older processors.
/end
Oh how convenient. A theory about God that doesn't require looking through a telescope.