I have not used topoprocess as I have GM and my own procedures for processing, so maybe I suggest will not work.
I run cgpsmapper from a .bat file in a command window - the output .img file has the same name as the input .mp file. If you have a final .mp file (with everything in one file, contour, hydro, etc),
try running cgpsmapper on it in a command window.
I remember OZ? mentioning adding .mp files together. cgpsmapper processes points, then lines, then polygons for each bit level. If an .mp file has these mixed, perhaps cgpsmapper has to spend a lot of time rearranging the data before/during the processing. I observe that 'on average' a file twice the size takes 2.5/3/3+ the time to process.
Again, please, someone tell me why a 10-12Mb .img is the right size? I have not heard anything about an optimum size for an .img file, however someone recently posted about Garmin files being in the 400-500K ? size (perhaps because earlier GPSr only had 24Mb internal memory). I would expect large files to slow performance of the GPSr. If Garmin only supports a 2Gb gmapsupp.img file with slightly over 2000 component files, about 1Mb per component .img file, why 10Mb file?
I just made some 30x60's using the new Census data which were this size for metro areas - I may test mixing quad/tile sizes to even out the variation in .img file sizes. I would appreciate it if someone could tell my why large .img sizes are desirable (if they are?)
Give me some specifics and I will create and process one of your areas and let you know what I get. 30x60 area is? 10m NED? Contour interval? Other data included as NHD hydro or Census hydro, Census roads,etc, GNIS, etc.?