Libgdx pre-rendering Bitmap font to pixmap texture causes slow in-game rendering

Question

Im using libgdx scene2d to render 2d actors. Some of these actor groups originally included scene2d Label actors for rendering static text. The Labels work fine but drawing ~20 of them on the screen at once drops the frame rate by 10-15 frames, resulting in noticeably poor rendering while dragging.

I'm attempting to avoid the Labels by pre-drawing the text to textures, and rendering the textures as scene2d Image actors. I'm creating the texture using the code below. (Inspired by Libgdx FPS drop drawing alot of text)

I assumed, and have read, that textures are often faster. However when I replaced the Labels with the texture, it had the same, if not worse, effect on the frame rate. Oddly, I'm not experiencing this when adding textures from a file, which makes me think I'm doing something wrong in my code. Is there a different way I should be pre-rendering these pieces of text?

BitmapFont font =  manager.get(baseNameFont,BitmapFont.class);
GlyphLayout gl = new GlyphLayout(font,"Test Text");

int textWidth = (int)gl.width;
int textHeight = (int)gl.height;
LOGGER.info("textHeight: {}",textHeight);
//int width = Gdx.graphics.getWidth();
int width = textWidth;
//int height = 500;
int height = textHeight;

SpriteBatch spriteBatch = new SpriteBatch();

FrameBuffer m_fbo = new FrameBuffer(Pixmap.Format.RGB565, width,height, false);
m_fbo.begin();
Gdx.gl.glClearColor(1f,1f,1f,0f);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
Matrix4 normalProjection = new Matrix4()

        .setToOrtho2D(0, 0, width,  height);
spriteBatch.setProjectionMatrix(normalProjection);

spriteBatch.begin();

font.draw(spriteBatch,gl,0,height);


spriteBatch.end();//finish write to buffer

Pixmap pm = ScreenUtils.getFrameBufferPixmap(0, 0, (int) width, (int) height);//write frame buffer to Pixmap

m_fbo.end();

m_fbo.dispose();
m_fbo = null;
spriteBatch.dispose();

Texture texture = new Texture(pm);
textTexture = new TextureRegion(texture);
textTexture.flip(false,true);
manager.add(texture);

Answer 1

The cause of this slowness was my misunderstanding about Libgdx culling. Scene2d does not automatically cull objects outside of the view frustum. Therefore my hundreds of shapes and labels were having draw() called when they weren't even visible in the camera. My short term fix for this was that I test whether an object is within the frustum during draw(), and as soon it's not visible I call setVisible(false) which tells GDX to skip the draw. I think a more elegant solution would be to set the culling area on the stage, but I would need to adjust it as the user pans the camera. I have not tested this since I've gotten past my current performance issues, but I believe it should work.

The answer comes from the same question on StackOverflow.