I assume, you want fast codec for video editing.
In previous years here was "codecs for editing", it was DV codec (used in miniDV cameras) and mjpeg (used in some video cards/"montage" cards). This codecs was implemented in hardware and mainly used for capture, but some hardware allows playback and even adding some simple effects and transitions. Yes, video transitions was implemented in hardware. Today this hardware and tricks is obsolete. But mjpeg still used in many webcameras which connected by usb! Yes, you usually got not "raw signal" from your webcam, but compressed by jpeg.
Today you can use DNxHD/DNxHR/ProRes, but mjpeg still good for creating proxy footages.
Other intra-only codecs: JPEG2000, lossless-jpeg, MagicYUV
Great blog post about codecs and proxy-editing: https://blog.frame.io/2017/02/15/choose-the-right-codec/
If you don’t have enough storage space, or if you’re on an
underpowered machine, then take the resolution down a notch. A lot of
huge-budget Hollywood films were edited in 480p just a few years ago,
so don’t sweat it if you need to lower your resolution from 4K down to
720P for the edit.
Also, you can specify "gop size=1" or "not use P and B frames" (it same) in almost any modern codec and get similar results. If you want REALLY FAST, I suggest to see on very old codec Cinepack - it was able playback video on even 80486 machines and you can find it today! Quality of Cinepack not perfect by today standards, but it enough for editing and preview purposes.