Speed up laptop

Hi there,

I am not sure if this is right place to post my topic, simply because I don't know what is wrong with my laptop to determine where to post. From that point I apologies.

I have Toshiba Satelite L555 laptop which is working reasonably good however sometime is slow regardless of specification. I want someone to guide me to check up if there is anything wrong.

My Computer:
AMD Turion II Dual-Core Mobile M520, 8.0GB RAM, AMD M880G with ATI Mobility Radeon HB 4200, MS Windows 7 Home Premium 64-bit

Antivirus:
Full (paid) version AVIRA PREMIUM SECURITY SUITE which working perfect.

Thanks to everyone who will try to help.