Hello, Let me start by saying that I'm very cheap and hate throwing good tech away... Own a 2009 Macbook (the old plastic unibody...think its the last one) running a 2.26ghz C2D and Nvidia 8400gs (yeah that's a bit old...) with 4gb RAM. Battery's about 45% strength from when I bought it (was practically restored to new 2 years in via warranty). I've been using it as my primary laptop since. Its about 5 years old now. Its been dropped, bruised, and just awesome in its durability. However, ever since upgrading to 10.10, its been slower at everything. Notice that my CPU usage jumps dramatically now when doing everything. Even Chrome seems to task it (you can see it chug when scrolling up and down). Gets super hot, too. Didn't do that before in Mavericks. Was pretty fast for everything besides compiling in Xcode, which I assumed was due to the slow HD than processing power. Multitasking is a slow PITA, but RAM doesn't seem to be an issue (its all in the green). My question is, do you think its a bad install? Will upping the RAM help? Or is my Macbook just too old for Yosemite? If it is too old, will a Macbook Air 11.6" be a good enough replacement? I like the portability and battery life to make it worthwhile, but need to make sure the processing bump will solve everything. Note: I primarily use my laptop for HTML coding in Textwrangler, web surfing, Excel, app coding in XCODE, editing videos for Youtube on iMovie, and light Photoshop (sometimes GIMP) work.