Your machine is perfectly fine. While maybe not brand spanking new, my wife's old laptop used a 2450M and was still perfectly functional and fantastic performance until she destroyed the LCD. Just make sure to read up on the Gentoo documentation so you know what optimizations to use, and which might break the system. If you have the patience, Gentoo is a nice distro.

I didn't bother with reading which optimization to use, I just used march=native and let the compiler work it out. IMHO, the main advantage of Gentoo is not better optimization, but its incredible configurability, which allows you have fine-grained control which software you want to compile with which dependencies, which software you don't want to see on your system under any circumstances, and so on.

I'll keep that in mind. :) Thanks, Timothy. :)

This feature sounds great to me. Thanks TobiSGD :) I'll try it soon enough.

But what about the "based VS. original" thing? What do you think about it? Do you have a different point of view, or agree with the previous posts? :)

The based vs original thing for me comes down to three things:
1. personal taste: If there is a distro (or respin) that you personally feel looks better and works better for you I see no reason not to use it
2. specialization: If you need a distro for a special purpose you may of course build it up yourself from a base distro, but why reinvent the wheel if someone has already has done all that work. For example, if I need a distro for rescue and data recovery purposes, I would rather go for grml (Debian based) or SystemRescueCD (Gentoo based) than their base distros, just for convenience. For the same reason I would choose antiX over Debian for low-spec hardware, just because the antiX developers have already done all the work figuring out which software to use for those machines.
3. extension: Some distros that are based of other distros offer functionality that the base distro won't offer (or where making the necessary changes is not really feasible for a single person). For example, if you like Slackware, but want automatic dependency resolution for your package manager you can go for Salix, which offers that. Or, if you want to have Slackware with systemd and Gnome you can go for the Dlackware project.

Of course there may be downsides in using derivatives. For example, while ArchBang is a fine distro that offers an Arch Linux desktop out of the box, I wouldn't recommend it to people new to Arch, but rather to experienced Arch users that want a quick and easy install. People new to Arch should IMHO go for the standard Arch install just for learning the basics about Arch, instead of getting a preconfigured installation that they can't really work with because they don't know the basics.

It also matters what type of derivative distro you use. If it is just a respin with a different desktop theme, wallpaper or default desktop environment/window manager, but no changes to the underlying system, then just go for it, if you like it. Everything that works in the base distro will also work in the derivative. If you use a more specialized distro then you may run into limitations that are not present in the base system. For example, while Kali Linux is derived from Debian it isn't compatible with Debian, so you may run into issues installing software packaged for Debian, in the same way that software packaged for Ubuntu (also Debian derived) may or may not run on Debian.

Everyone left out the communities, while it's not technical finding a community that matches your personality goes a long way. The human is always the slowest part of the computing system so the biggest gains com from that aspect.

Thanks a lot for your insight. You don't know how much I learn from other people's insights, It broadens my horizons. It's not just about opinions, It's the small information that each one of us adds to the rest. :)

Do you mean that joining distro-specific communities will also help? Sorry I couldn't get your point. If you please, Elaborate more. :)