Blender Animation Playing at 3 4 FPS After Adding Keyframes to Organic Models. How Can I Make It Smooth

Very nice and clean looking scene you have there. Impressive.
Unapplied modifiers are usually the culprit and that i5 processor is probably struggling.
Check these out for an overview of potential tips that are employed.

• Material view to solid view

• Upgrading to the latest version of Blender

• Enable Simplify in Viewport Options (max sub-divisions to zero)

• Hiding objects

• Disable geometry nodes in viewport

• Swapping in proxy objects

How to Optimize Viewport Playback in Blender

Another take focusing mostly on the Simplify in Viewport approach
How to Actually fix your FPS in Blender

Experiment with a file copy to not destroy the work you currently have.

Your laptop should handle Blender fairly okay, so it’s probably the scene being too heavy 😅 Organic models, high poly meshes, modifiers, or textures can kill viewport FPS fast. I’d try solid view, lowering subdivision, and temporarily disabling heavy modifiers while animating.

@NubDevice Thanks for the response. Somehow, I forget that I have asked a question on this forum. So I apologize for the late response:

1) I did not know that unapplied resources take resources, so I have applied them all.
2) On solid view, the FPS becomes better at 6 fps. Still not the ideal.
3) I am working on the LTS version, and since I am on the latest LTS version. I am not going to upgrade to the non LTS latest version.
4) My objects are already hidden, although I have removed some objects.
5) I have not used geometry nodes.
6) Swapping in proxy objects I did not know that what is this. So, I have to see it. If I found it useful I get back to you.

Thanks for these two YouTube video link: I will look at these.

@Gamecraftor Thanks for the response. Somehow, I forget that I have asked a question on this forum. So I apologize for the late response:

Right now my scene have 298,212 polygon. I don't know that for my laptop the polygon is high or low. As for organic model each organic model have 7K to 12K polygon. I don't know it's high or low. I have appplied all the modifiers. On solid view the FPS improve, but still it's 6 fps now. Not more then that.