In Apple we trust!

Now I understand the difference between h.264 and ProRes.
One more thing folks, if a h264 video file is natively compressed, then when it is transcoded to ProRes, will it be larger file size? For instance: if I have a 200mb video clip in h264, then if I convert it to ProRes, will the clip be, say, 250mb? I am thinking in the lines of winzip(?) or when you compress a file to reduce the bytes. Is this why ProRes does not tax the system as much as a compressed file such as h.264?
I understand the point that a ProRes file is easier to add effects to including color editing or after effects, so it is post edit of an edit? The h.264 file will use more system power, hence the longer time to achieve the same product due to editing in a compressed video file?
Thanks again guys for taking the time to answer our questions.
EDIT: I watched the video and pretty much the material covered in the video is what you guys said all along. Not that I questioned your answers. I apologize gents as I misunderstood the meaning of words such as "after process," "adding effects," and "transcoding." I did not understand neither the stress on the system nor the time involved to transcode video files.
Although transcoding into ProRes consumes time, but what about the final product? If I use the h.264 clip, add effects to it and change the color, will this tax the system more so than just transcoding into ProRes to begin with? Which method supports a 'weaker system,' editing natively or transcoding the original file into ProRes? I hope these questions are clear. Thanks again!