On Linux I use obs-v4l2sink https://github.com/CatxFish/obs-v4l2sink

On Windows I have tried OBS VirtualCam https://obsproject.com/forum/resources/obs-virtualcam.949/

Both of them work very close to real time for me.

Maybe your computer lacks hardware acceleration?

Linux is a quagmire, but latency problems on OBS boil down to needing a fast computer, with a powerful graphics card to encode, and carefully configured audio (the default pulseaudio setup is usually a problem). Using JACK or similar will fix a lot of trouble, but really you just need horsepower to process video at HD resolution in real time.