Which should be the higher priority in TMPGENC (using Plus 2.58 version), the AVI2(OpenDML) or the Directshow Multimedia File Reader?

When I'm converting a Divx avi file to SVCD, when I'm attempting to preview or use Source Range (to split into 2 mpgs for 2 disc set) I get a system freeze for various lengths of time. It appears that my hard drive is churning away, and eventually the displayed video will "catch up" and I can move the slider again, but at another point it will freeze again. I guess it is taking a while to decode the divx? I have Divx 5.02 installed, btw. Would changing to the Directshow filter make any difference in this or in conversion quality?

Oh, I have a 1.7GHz P4, 256MB PC800 RDRAM, 80GB C: drive and 40GB D: drive (on seperate IDE channels), using WinXP Pro SP1.