Seems a bit extreme. You're using a light with a brightness of 3400 (your 1000 strength light material has no texture source, so it defaults to linear colour grey, so many of the samples are only doing a third of the work they could be doing) So 2/3 of the samples are wasted. Your material is mid grey, so half the brightness is lost off the first bounce then only half the brightness is received, so 75% of the samples do nothing. Multiply the above together and it means 90% of the samples arent doing anything useful.
Adaptive sampling is off so 90% of the samples are flying off into space to do nothing. We're down to 1% efficiency now? 16 light bounces are very wasteful on a scene where only 1-2 bounces can possibly have a meaningful impact. So we're down to... 0.1% efficiency in terms of render time.
Youre using geometry to emit light instead of a light. Octane can more efficiently render a scene if the bulk of the light comes from a light instead of polys.
When you have this many samples, you can 100% turn the denoiser on.
And finally, the scene is so utterly beyond overexposed, you're effectively cranking a noise with a brightness of 5-10 (0-255 scale) up to 100, which is going to exaggerate the noise you see. This is the worst case scenario of worse case scenarios.
As for the c4d physical engine version. You're using irradiance caching, this just slaps a bit of light on, blurs it together than adds it to the brightness. Effectively c4d is running a denoiser on the secondary light, something you're not letting the octane engine do. An apples to apples comparison would be setting physical to QMC + QMC with 16 bounces, but you can't because the slider tops out at 8 bounces.