This are the Settings I used at last, as suggested by valerostudio:
() Set the "Max. subdivs" to 100 (one hundred). Leave the "Min. subdivs" to 1. (Done)
() Set the primary GI engine to Brute force GI. Do not change the subdivs. (I left the Irradiance Map option, there was no "brute force" in the version of vray i'm using)
() Set the light cache interpolation samples to 5. (I assumed this is called "Filter Samples in the version i'm using, if so, done)
[] Noise threshold 0.001
The rest of the sugestions were already set by default.
I think the render improved a lot, feel a lot better with the result, i'm posting the image for your critics if possible. Thank you!