With my 8 GB RMBP swapping about 2 GBs each day to disk, I decided it's time to try to replace applications using excessive memory. First thing I noticed is that Safari uses 5 times more RAM, when the same tabs are open, than Chrome. So I switched. Secondly there is a task called kernel_task that uses about a GB of RAM all the time. I don't see this happening on my iMac. What is it and can I turn it off? Also, Mail uses about 400 MB all the time and a process called WindowServer about the same. What's the latter?