There was a big Nebulosity 2 update today I think and one of the changes is massive improvement to the download time for the Windows version. Assume that's the one you're using? Apparently there was some issue with Canon's Windows SDK but it's resolved now. Download times gone from 30s or to so 5s(?).
You might want to try that, see if it helps? Direct link to the 2.3.7 version:
http://www.stark-labs.com/prerelease.html