I'm a professional broadcast editor having to use Premiere full time. Mostly I like the NLE but in almost every large documentary project there is always some bad media that causes massive playback issues, which is really frustrating when I need to work quickly.
While I like the fact you don't have to transcode everything to a native format like in Avid, therefore avoiding massive and expensive workflows, I do think Premiere should assess all media upon import and tell you if it wont be able to play it back well, and if it can't then it should ask you if you'd like to transcode this media to a more premiere friendly format using Encoder, eg Pro Res.
Something like this would help all projects run smoother, without constant lagging and playback issues. Im on an iMac with 32gb RAM, 8gb graphics, 4.2 GHz Intel Core i7 - this should be plenty to run Premiere!
Editing, Formats, Freeze or hang, Import, Performance
a pre-assessment would have to play all the media and determine a green light for playback. this would require premiere to play it before it plays it and compensate for the fact that the timeline, audio waveform need to be shown while building cache. I highly doubt this plan would really work. It sounds like you have h.264 media. either get a intel quicksync processor or auto ingest proxy while you hold your breath.