One of the beauties of Non Linear Editors is that at final output rendering, it goes to the source. It is not rendered twice.
The single most confusing subject I've run into trying to learn editing is how this works. Here is what I think happens.
First, you have to have a project setting that accepts your source files so that you can work in real time preview with smoothness. The computer is doing "real time project rendering" for preview. So, if Ann's suggestion works during the editing process, you're fine. In other words, you may not NEED an exact match between your source footage and your project preset. Let PrE pick the best it can when you slide the first clip to the timeline.
Second, when it is time to make your final product(s), you set the "output render" or "transcode" setting in the Share+Publish area. You might need something optimized for YouTube, an iPhone or Hollywood. The editing software then looks at what you have been doing in real time, goes to all the markers and transitions you have set and makes an entirely new file, the "video", by reading from your 50Mbps source files.
Somewhere here there is a long post from an Adobe tech who tried to explain it to me. He emphasized that there was some relationship between the project setting and the output files, but the most important part was the output settings.
In the Share+Publish section there are a lot of presets. For some you can change the frame rate and bit rate. You should find something pretty close.
Your GH3 is so new, I've read little about it. A 50 Mbps rate is twice what we've had at the consumer level for the last few years. Have fun with that camera!
Bill
