I am using firefox 30 and my firefox crashes frequently when i use facebook,while watching youtube videos,closing a high-loaded tabs,etc and also shows "plugin-container.exe has encountered a problem and must close." and another problem is that while watching youtube or using fb plug-container.exe and firefox.exe both uses about 500MB of my RAM and currently I have only 1.5GB RAM which makes pc working slower. I had recently disabled hardware acceleration but the crashing problem still there.

Please provide me a Fix.