Hi Sergio @Sergio4624,
It’s looking good!
Render times and viewport performance are highly dependent on your computer, especially GPU, so unless you have the exact same specs as me, you’re likely to see differences. I do have a powerhouse of a PC. Omar is right, you can compare the settings one more time to the lesson and see if you missed something. But it’s quite normal for a 4K render to take a while.
As for the gamma: In simple scientific terms it’s a correction of how the light, bright and dark areas, are represented. We can get very complicated on the topic, but the truth for me is I just play with the value to get the look that I want for my scene. It’s also influenced by your monitor and how it represents colour and the settings for it. It’s best you just move it around a bit until you find the look you’re happy with.