LexManos

This definitely sounds like a over zealous anti virus, so try nuking that during the install.

You need to install the server and upload every file that it creates to the server.

I am unable to reproduce this issue in any environments. As Dies said, from external views it'd look like java is eating all the memory, but that's becuase that's how the JVM works it manages its own memory without releasing it to the OS. If its inside MC/Java, you can try making a meory dump with jprofiler or something, may give you a better idea whats holding the memory. But like I said, I can't reproduce this in any environments.

You need to to change your java version. The version you have installed does not have LetsEncrypt's root authority. https://adoptopenjdk.net/

Really old Minecraft versions are no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.8 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.7 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support. Also, this is a English only forums.

No, there isn't. Its important information to show the loading hasnt frozen.

Really old Minecraft versions are no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Something messed up in our promotions file, i'll take a look. It doesn't effect anything in game. Its just a messagge.

Dont change the fact that we don't support custom launchers, as they are against Mojang's wishes as well as basic common sense of not enterring account info into 3rd party stuff. And we also don't support installing things with non-standard systems. AND 1.7.10 is years old, you should update. It still works, you can still use it. But if you have issues its on you to fix it yourself.

1.7 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

... Why did you install optifine on the server?