You could first export a DV encoded .mov file in FCE, which should be 220-440MB in size. That should be quicker as no proper re-encoding is done.
Then use MPEG STreamclip (
www.squared5.com) to convert the DV .mov file into a H264 .mov file, for which you even can determine the final file size and if the file is being multi passed (the more passes the better the image quality if the bitrate is variable).
See if that is any faster.
PS: Are there many effects in the final sequence?