Optimization

This is indeed not the right place.

• If you want to talk about UPBGE, then seek UPBGE's communities. They are two different softwares.
• If you want to talk to developers about Blender's development, blenderartists.org or perhaps devtalk.blender.org are better suited.
• Here on RCS, the Blender community posts and discusses feature proposals, developers rarely come here to discuss things.

Most of the questions you have about whether Blender have or plan to have X or Y feature can be answered by searching the manual (for what exists) and projects.blender.org for what is being worked on by the devs. You can also check the developers' blog at code.blender.org where they often post things like development projects and roadmaps .

1.Does blender (Eevee) have rendering optimization methods? I’m talking about Frustum Culling and other Cullings (Backface, Occlusion etc), Streaming

Cycles have some culling options under the Simplify tab:

Eevee doesn't have these options, though, as it is a raster engine , I'm pretty sure objects out of camera aren't calculated at all, and shading effects like AO and reflections are screen-space. See Limitations — Blender Manual .

But I think you can make it with GeoNodes if you want.

Back facing is available in both Eevee and Cycles. Occlusion (as in, not rendering objects behind others?) happens only in Eevee (raster engine again). But again, if you want that in Cycles, I bet some GeoNodes can do it.

No data streaming I've ever heard of

2. Why is blender so bad with animations at the moment? The load on the system is massive. This applies to everything that affects the mesh.

Performances in animation have been greatly improved in the past years and might see even more changed in the near future as part of the Animation 2025 project .

3. Is it planned to introduce VAT (vertex texture animation)

I haven't seen any mention of VAT on the project page, so I doubt it is planned or even discusses. Plus it doesn't seem to be a widely spread technique to begin with, in my search I found mostly posts about it from SideFX (Houdini) for UE5.

I have found this proposal on RCS that seems related? Introduce "Timer node" and "Morphing node" (Vertex texture animation) ⁠— Right-Click Select

But if not, feel free to make a well documented proposal here for Blender to include this, with details explaining what it is, how Blender would implement it (that includes creating and using VAT).

4. Are there plans to add any methods to optimization?

Blender's performances are constantly being worked on.

5. Do you think about returning BGE support because many people continue to study it and create games.

I think this third-party post sums it up pretty well. But in short: No.

It would be great to just at least keep in touch between the UPBGE community and the developers of blender

Nothing prevents either part of doing so. But I think they don't really have much to keep in touch about, at least for now: they do not work on the same thing. Blender devs make a 3D creation suite, UPBGE devs make a game engine. That is based off Blender, but it still means that they both what different interests.

(If we talk about UPBGE, then the load on the Depsgraph of the inode is simply colossal)

Although I do not know UPBGE, I would NOT assume it is the same as Blender. Being based off Blender doesn't mean UPBGE is picking up every feature and fix that happens on Blender, nor that things like performance - and how to handle them - are the same.

Render engines, used in blender, in not a game-ready. In things like Culling would be used, shadows going to be corrupted since it is a real time renders only.