Do a 'Pass Through' Composite node make the scene faster or slower than a 'As Bitmap' Composite node?

Hello.

I’ve read about ‘Pass Through’ option of Composite nodes in the Harmony 12 documentation.
This might be a stupid question, but some things aren’t clear to me yet.
I’ve got a pretty big scene and i want to know how to get it a little less heavy, calculation wise.
I know what ‘flattening’ means, but i don’t know if it’s faster to work with flattened images or just with the original drawings/effects.

So should i make as much Composite nodes as possible change to ‘Pass Through’, or keep them as ‘As Bitmap’?

Thanks in advance!

Flattening wherever possible will provide the fastest most efficient results.
Use “Pass Through” when “As Bitmap” causes an effect to fail.