HDMI long startup time, wtf?

so i ordered an hdmi to dvi-d converter for my monitor off ebay. i had previously been using the microsoft vga cable and i wanted to see if the hdmi actually looked any better. i've noticed that yes, it looks slightly better, but the weird thing is that when using the HDMI cable, my 360 takes a lot longer to boot up. i turn it on and can hear it working, but the 360 logo doesn't come up for 20-30 seconds whereas it usually comes up immediately when using the vga cable. is it normal for the 360 to take longer to boot up when using the HDMI cable?