Are people who ask this kind of stuff, making us spend a lot of time to read this kind of bullshit, naturally stupid and have nothing really useful to do with their free time?

Some of my recent customers' computers face this issue once in a while. It seems that people forget about hardware cleaning. Most of them think that just software maintenance is Ok. I've once found a high-speed computer performing tasks really slow. I just opened it and cleaned it up. The display card was trully dusty. After that, the computer went back to its usual performance.
Also, take a look at Event Viewer, seek for warnings and errors. That may give you more clues about what the problem can be if it keeps slow after cleanup.

I've learned some tips from a general security consultant while he was being interviewed on a TV show.

I don't remember all of it, but one of the tips I remember by heart is: Always insert the wrong password first. Then, you go back and put the correct one. If there is anything "listening" to your password, it will catch the wrong one. I don't know how effective this can be, but you know, any defense you can use is worth when it comes to your security.