Best Lossless Video Encoder For Editing
I'll start by pointing you to another answer I wrote before, roughly covering the different kinds of codecs.  

(Nice edit on your question, by the way, removing the file size limitation helped figure out what you were after.)

My recommendation (again) will be to either use ProRes 422 or Cineform as your intermediate, probably via Magic Bullet Grinder or GoPro Cineform Studio respectively.

Either of these codecs will give you good decoding speed, and both will work with Vegas and After Effects.  Any workflow that involves transcoding and not capturing natively to your editing codec (such as with ProRes on an Arri Alexa or a Cinedeck), is going to sacrifice time for processing, but in your case, it seems like that's a necessity.