InstaDMG system slower to boot than DVD installed system

I have a hybrid instadmg style w/radmind deploy method. I was noticing slow boot times on my test machines of SL as I get this school years SL update ready. I'm working with original 10.6 update DVDs that came with our last big purchase of Macbooks and the 10.6.4 combo updater. Using the osinstall.mpkg onto a partition, and then restoring that partition to another partition results in boot times in the 50-60second range on my lab AL iMacs, while using the installer on the same DVD to do an install on a partition results in an OS install that boots in 20-30 seconds? I'm trying to use the mpkg under the assumption that I want an "unbooted" image Has anyone else noticed this? I've replicated it several times. Is there some post processing being done by the SL DVD installer that is not being done by just the regular installer? This is more a question of the InstaDMG methodology rather than the reference script - as I'm invoking the osinstall.mpkg install outside instadmg. Does anyone know what steps the DVD installer is doing beyond the package install that would effect boot times? I've zapped pram, set boot volume etc. -Preston