I just finished a large 4K job and the edit was a nightmare. Someone suggested that I look into proxy files. Today I read up on what a proxy file is but I found no info on how to record it. Is it recorded at the same time as the 4K file? I assume the two file structures must share a common time code.

Someone, please set me straight!

Your editing software (if it has that feature) creates a low resolution substitute called a proxy so you can edit quickly. When you export it uses the full res video you filmed.

I think the workflow is to transcode the original files into lower rez proxy files with exactly the same filenames as well as the same folder names and structure.
Then open the project using the proxy files and do your edit.
When finished, change the name of the proxy folder, or move it- this will offline all the proxy files.
Reopen the project. When you are asked to locate all the missing files, point the NLE to the folder with the original full rez footage. It should relink the entire edit to the original files.

Some cameras can actually record proxy clips, some require additional cards to do so or attachments. But like the others said, most NLE programs have a generate proxy option. Here is the option in FCPX.

What editing program do you use?

Edius 8 Workgroup. My computer is a HP 8400 workstation with dual Zeons, Quadro 4000 graphics card and 32GB of ram. It is old and struggles with 4K.

Can I assume the proxy files are clones but of low resolution? After completing your edit with the proxies, you just link the raw 4K files, start the rendering and exporting and come back in two days?

Get a new computer and then you won't need the hassle of proxies at all. And if your computer can't handle 4K, what else is it doing slowly? Time is money. Upgrade now.
BTW, I edit with Premiere and grade with Resolve 4K Sony RAW, S-LOG, XAVC-I, XAVC-L, etc. on a couple of 2014 MacBook Pros with only 16GB of RAM without any trouble. So you don't need to have some big huge custom made PC muscle car of a computer.

Edius 8 Workgroup.

That was the most important part we need to know :) You don't have to buy a new computer yet, Edius has a few tricks up it's sleeve which you can try first.

The first one is lower the preview resolution which makes a big difference in realtime playback, in your preview window in the top right corner you will see a selection box that has "full" as standard preset, select that box and select 1/2 or 1/4, that will lower your preview quality but makes a big difference in ease of playback.

Second option is to make proxy's, edius had this build in,

First select "system settings" then "application" and "proxy", you have 3 presets, "Small", "Medium" and "Large", if I use proxymode I always select large as it makes a 1920x1080 proxy file which is about half the size of the original and visually almost identical to the original. I believe Medium is 1280x720 and Small even less, the last 2 files are a lot smaller then the original. Just make sure you have enough space on your harddrive.

select "Mode" and then "Proxy mode" and Edius will start to build the proxies which are smaller files with much less compression, note this can take quite a while depending on how much data it needs to convert. You can follow the progress in the right bottom side of the Edius screen, it will show how many files it still needs to convert.

Once that is done you can toggle between proxy mode and original files by selecting "Mode" and "Proxy", when you are in proxy mode the files on the timeline get a clear different pattern and then you can edit without any issue, once you have done editing turn off proxy mode by selecting mode and proxy again, the pattern on your files disappears meaning you are now working with your native files again and you can start exporting.

Your processor doesn't support quicksync meaning the CPU doesn't have a build in GPU, if you ever want to upgrade then either get a multicore CPU like a 10 core I9 7900x or if you are on a budget a I7 8700k which is a 6 core but edius can use the GPU on the CPU to accelerate rendering a lot up to a point where it about can match the 10 core processor speed.

Have a look at David V Clarke's youtube channel, under "What's new in Edius 7.5 " Proxy files.

He has lots of very good tutorials
Peter

Premiere CC does it with ease. Funny, I thought I was naive to it when I started last year, and this year thought I was behind because I don't 'shoot' proxy files with my X70, I do want to try that but not sure of the workflow. I admit it can add steps and some rendering time, but it's pretty seemless.

Essentially you almost 'export' your footage to a smaller resolution file, then edit using those smaller files. When you encode the final product Premiere automatically knows to use the higher end version and in fact you can toggle between the two when you edit if you so desire. It definitely quickens the editing.

I believe this was the tutorial I watched to learn it, worth watching even if its just to grasp the concept of it even if not using Premiere:

https://helpx.adobe.com/premiere-pro/how-to/proxy-media.html

Thanks everyone! Now I am an expert and ready to sell instructional videos on the subject....not.

I am setting Sunday aside for trying to edit with proxies. I am sure I will be back Monday with new questions!