Cycles CPU speed compares to Arnold/V-Ray


i have a question to the renderspeed of cycles in CPU-Mode compared to other pure cpu-renderer like V-Ray or Arnold. Is Cycles close up or slower/faster? I ask this, because, every time, when i have a bigger project, i must render out with cpu, because i run out of videocard memory. So at least i have only cpu-rendering avaiable. But since i heard, that cycles is opimized to gpu rendering, i wonder if i have a lot of time lost then with cpu.

Speed is very relative. It depends on the complexity of the scene & user’s skill.

So my first advice is:
Show some of the cases (or share your experimental/study/test scene) you mention, so all involved can give you their best, most efficient answers without guessing & wondering what your final intentions/goals/artworks are.

But basically, if you don’t do complexity, than it doesn’t matter (usually, speed wise rendering engines (using same/similar algo. base) are somewhat on pair, so it boils down to advantages in other areas (workflow, pipeline, memory efficiency, volumes, caustics, GI, particles… all kinds of specific tasks).

Then again, if you’re really eager to know - test (become experienced)!