Using Forge 2315, Cavern 1.7.9 and Cubic Chunks build 0.0.615.0.

Game loads, but anything above a certain height (it seems to change each time, in the screenshot example, Y=94) or distance from start location, does not render. Attempts to fly outside the range causes player to get stuck-- player can no longer move but can look around, examine inventory, pause, etc. Teleporting commands do nothing.

This seems to only happen with Cavern and Cubic Chunks together. There is no crash report.
FML Client Latest log: https://pastebin.com/LzMHpDsx

This is most likely my issue, and it's most likely that something freezes the server.

Now is worst: the world can't load because a strange java memory error.

Create a issue in Cubic Chunks Issues then

The problem is a strange memory error, Minecraft needs a great amount of memory with only installing the two mods

You know that saying "srange memory error" doesn't give me any information? Actually giving the error log woudl be much more useful.

Here you have:
fml-client-latest.txt
I could load the world but Minecraft was using 2G of RAM and the game freezed because of the overload.
And I have only 3 mods installed (Cubic Chunks, Cavern and OptiFine).
The error i was talking was the error that Minecraft gives when it runs out of Memory

I will look into it, I already forgot about this issue.

That's why it should be reported to me instead of to other mods...

First, if you have been on my discord for some time you would know that right now cubic chunks doesn't clean up worlds correctly after quitting singleplayer worlds, so they remain in memory. This is most likely the cause of your memory issue and is unlikely to be releated to this mod.

If the server freezes with this mod, this is most likely an issue with Teleporter. The log you gave also doesn't show anthing wrong. No crash, no out of memory. Just loading and unloading the world several times.

I only executed Minecraft and created ONE TIME one world without quitting it. I only loaded it one time, and the log doesn't show anything wrong because isn't a crash, its a world freeze. And i could load it because i removed the rest of the mods, with they I needed more time to create the log Anyway, I can't play with the two mods because i had only 2G to give to Minecraft, the rest is for the system.

Looks like cubic chunks is trying to load all the cavern dimensions when loading the world, this may be using a lot of memory. I' not sure if it happens in vanilla or not, but it probably doesn't.