Seriously, I had to just do some simple edits to shorten a freaking zoom tutorial...so I got H264 to use and yeah its garbage but regardless. I disabled what is ENABLED by default and I went from extreme lag and stuttering to make it impossible to time a cut to lear real time playback. Just spread the info. Adobe I beg you NOT to touch this.
Preferences > Media > DISABLE H264 Hardware accelerated decoding.