Other ways to speed up your computer include: 1) Defragmenting (make sure you aren't defragging an SSD though). 2) If you have under ~20% of disk space, uninstall unneeded programs, delete unnecessary files, and empty the recycling bin. A hard drive near capacity takes longer for it to search through data. 3) Update outdated drivers. Newer drivers will likely be better performing (though often may be miniscule at most, or may cause its own problems). 4) For malware scanning, I'd recommend to download and install Malwarebytes Anti-Malware. For general cleaning, CCleaner (proceed with caution and if you modify the registry, make sure to back it up).
Most computers actually contain what is essentially a miniature Quartz watch inside them that is powered by the CMOS battery. This is evident in the BIOS (or UEFI in more modern computers) since the clock still ticks without the network. Without power, it continues to tick due to the CMOS battery, again evident by booting into the BIOS/UEFI. When you do end up getting internet, it'll recalibrate itself with a server, all the while with the miniature Quartz watch still ticking.
They're for different audio products. For the most commonly used ones, in general (but not always), the pink jack is the input jack for a microphone and the green jack is the main line-out jack for extraneous audio devices / control devices such as amps, speakers, or headphones. The other colors are for more specific / specialized devices, and the jacks included depend on the motherboard the computer has. Two more jacks include the black jack for a rear speaker and the orange jack for a subwoofer.
For blue, likely no. Regardless though, it depends where the light is coming from. If you have no problems, then it is likely that they are just status indicators or for aesthetics. One exception would be the motherboard's LED error indicator. If you do have issues, the first place to look would be here. It settles on a code after booting up (or failure to boot up). After determining the code, you would then be able to check either online or within the manual (for the specific motherboard) to determine what the code is telling you.
As an aside, the safest option BEFORE cleaning the computer is to completely discharge the computer. Any lingering electricity may cause a short circuit when attempting to clean the computer. To discharge the computer, simply unplug the power supply unit's cable from the power supply, switch the power supply's switch to the "off" position," and then press the power button one or two times. If there is still electricity inside when you press the power button, you'll see the computer momentarily turn on and then shut off as it loses the rest of the electricity. The safest cleaning supply would be compressed air, though do note canned compressed air can condensate. This primarily occurs when the can is held upside-down. Another often used cleaning material is 99.9% Isopropyl Alcohol, though more care is needed, especially near more sensitive electrical components such as the processor. It is capable of conducting electricity. The vapor is also highly flammable, so work in a well-ventilated environment and...