Nah, I regularly clean the inside of my laptop, it has exactly zero dust in it
Also, it's a not-so-new Win8 installation, so everything is settled down. I have disabled indexing, I have disabled Windows Update (+ I suspended TiWorker.exe from ProcessExplorer), I even disabled themes, and it's still 30-70%
Since Win8 has improved driver system, I can put Win8 on an external drive (which is how it's installed for me), and if I plop it in my Potato Toaster (this is how I call my underpowered main PC), the idle CPU usage is 0-1%
I'll try out Win10 later just for a performance comparsion, but I'll stick with good ol' Experience
Since others can use it perfectly fine with their similar specs, either you'll have a good experience or there's something else at play. Something more than just "it's crap!"