Yes, that’s normal for H264 streams via a browser (the app uses browser components too, AFAIK). You can possibly improve this by reading up on go2rtc. This is now built into HA.
There are too many things involved with cameras to iterate all of it here, unfortunately (and there are others that will know a lot more than me on this subject). Some people integrate their cameras with something like Frigate before exposing it to HA.
There’s also an abundance of info here: I tried all the camera platforms so you don't have to.