Hello everyone. I have already read some threads about the Yosemite' performance. I have a Macbook Pro 13", Mid-2012, 2,5 GHz Intel Core i5, 4 GB RAM & Intel HD4000. Since updating to Yosemite, I notice the entire performance is VERY slow, specially with Safari & Mail. Safari lags are absolutely annoying, freezing all the apps. The same happens with Mail. I though, initially, this lag happened because of the caches, spotlight, etc. and I was hoping it would get better day by day. But I can't seem to experience less lag than before. Working with SPSS, Microsoft Word, some PDF's open & Safari... mission impossible. Is it worth it to upgrade the RAM? I never though about that, because I never felt the need to do it. Is this happening with other people, too? Thanks.