"My MacBook is frozen and it will not shut down. What's wrong?"に関する回答-If OS X does not respond totally, the best solution is holding the power button to force it to turn off. And then open it again. - Macbook gets laggy really? You can either quit some running heavy app and other software solution such as cleaning up your Mac and decreasing the items in startup list as a temporary solution or upgrade hardware to speed up your mac for long-term smooth working.