Best Lossless Video Encoder For Editing I'm looking for a good video encoder to compress HD files for editing within Sony Vegas Pro and Adobe After Effects. 

What video codec would provide the fastest possible encoding and decoding? Also, what are some recommended encoding settings?

The video files must be usable in Sony Vegas Pro and Adobe After Effects.

EDIT: Source Clip Info:

Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High@L5.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 8 frames
Bit rate                         : 4 334 Kbps
Width                            : 1 920 pixels
Height                           : 1 080 pixels
Display aspect ratio             : 16:9
Frame rate                       : 23.976 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive


The container is Matroska.
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.