Minecraft has always used Java’s code system. It’s fine as long as the particular version you are running doesn’t have security exploits or load adware/crapware, which most versions tend to do right after an update. But if you wanted Minecraft to run as fast and smooth as possible you had to have that security-risk, of a software, up-to-date.
For the past couple months or so Minecraft has had a launcher.exe that you started before Minecraft. In a recent update, in the advanced settings, you can enable a feature that allows Minecraft to download a standalone version of Java that only runs while playing Minecraft. It can even be a bit of a performance boost and can even raise you FPS by double for some.
Now the only thing we are still missing is this wayward Modding-api that we were promised way back when.