Is my i3 2.5 GHz TOSHIBA laptop really not powerful for Windows 8?
Because I have noticed the fan is spinning a lot without even running a game and sometimes I encounter slow browsing and when I close a tab in Mozilla, it slowly closes... Laggy.
Yes, your laptop is plenty powerful for Windows 8 CP. My desktop (check out my specs) has only an anemic AMD Athlon 64 X2 3250e, running @ 1.5GHz, shipped with 2GB DDR2 RAM (I upgraded that to 4GB), and was designed to run Windows 7 64 bit. Windows 8 CP coasts along on the PC, whereas Windows 7 Pro x64 made it scream at times.
At first, I was pleased, as it was my first new PC, but after much reading, I found that I could have spent another $100 and had a Core2Quad & 6GB DDR3 RAM (would've had to buy a monitor). At the time, I was ignorant about computer specs, either it worked or not. My primary concern was my ISP, having a decent connection.
To answer your question, your CPU is 1GHz faster than mine, is far more modern, and I'm assuming that you can install 4GB RAM or more (the more, the better, although 4GB is considered the "sweet spot" by many experts & IT Pros.
Probably the reason for your fan running a lot is processes running that you don't realize is running. You can open "msconfig" & find these unneeded startup items (make sure that you don't need them). Also, on Firefox, run no more addons/extensions than you need. That helps alot (also applies to Chrome).
Cat