I have a Macbook that is unusable slow. When i push a button or try to get a drop-down menu i need to wait 15 seconds. I have replaced the harddisk with a 120gb SSD and the 4gb memory is replaced with other apple compatible memory. I have a clean install of Mac OS on the macbook. The Macbook is still unusable slow. Installing Mac OS have cost 12 hours. This is already an indication that the Macbook is slow. Resource usage is low. cpu 90% idle, mem usage 1,7gb out of 4 gb, hd usage 20gb IO 0 read sec. / 0 write sec.. Update: Macbook Pro medio 2012, 120gb os partition, 20gb in use, OS El Capitan.