Real-Time Playback Lag in Adobe Premiere Pro

To go along with the Neil has said, we'd like to see some info on your files: 

You can use the free MediaInfo program to get info on your clips. Get the program from the link below and using the 'Tree' view post a screenshot of your clip info: https://mediaarea.net/en/MediaInfo/Download

Most mpr4 media is long-GOP, which is the hardest stuff for the processing system to work with. AMD systems haven't been noted for often even having any H.264/5 hardware encoding/decoding bits in them.

So that might be a large part of your trouble.

"Long-GOP" means there's a fully complete image frame every maybe 9-60 'frames' of captured video. In-between those frames are simply datasets ... charts... of 1) the pixels that have changed since the last "iframe", 2) the pixels that will change before the next iframe, or 3) both.

So to show the next frame, the computer has to sort out which iframes are needed to be decoded, and!!! ... decode all the other frames between those iframes and the next frame to be displayed ... and store to RAM/cache ... again, just to play back the next frame.

Which is why drone and phone footage is often considered a slog in pro editing circles. As those make heavy use of the capabilities of the chips in the devices to do incredible encoding practice to cut down the amount of data actually written to the card. Every device making the stuff has a chip inside just to do that bit, that is set between firmware and all a bit differently than other devices.

But your computer doesn't have all those different parts, and if you don't have the specific hardware with H.264/5 decoding parts in your system, it's a processing slog.

@11020311