When im using facebook an every time.,,.....

Hello,
when im using facebook an every time in my Laptop(Installed Windows 7 Ultimate) getting verry slow, & not able to use any programs. its getting systemhang in all programs / every time suddenly it shows like system is not responding. In task mngr shows like - iexplore memory using 443,653 K, (Processes 63, CPU using 16%, Physical Memory] 90%).
plz someone help me....plz