There could be any number of reasons. Without knowing what the content and make up of the video is we can only guess.
This morning I put together a test of scrolling videos for another thread. I used the same clip 7 times in 7 different tracks. Producing the 51 second video took 4:36 with the audio included in all tracks. I removed the audio and the production took 55 seconds. Clearly in my case the audio from the 7 clips was the factor that changed the producing time.
My system specs are below.
Hal
OS - Win11 Pro, Alienware R13, CPU - Intel Core I7-12700KF 12 CPUs), 16g DDR5 4400 RAM, Video - Geeforce RTX 3080ti 12g, PD11 & PD365
My YouTube