Video rendering time and number of triangles

Hey there!

I am faced with a misunderstanding of one point and can’t come to a solution.
I have a project with a total of about 2.7 million triangles for all meshes. I optimized this number manually for each mesh and I got about 600 thousand triangles in project. I decided to check how the rendering speed would change for a video with baked lighting. As a result, it turned out that the rendering speed decreased and I began to record the same video longer.
I would be glad for any help and hints as to what could have gone wrong.
Thank you!