Have had this thing for years, mid 09' 13" 2.53ghz etc, and actually still use it even though I have a 15" Retina. So awhile back I kept noticing the trackpad was getting hard and hard to press. Low and behold case of the swelling battery, it actually started separating the case as it apparently stripped the screws. New battery, new screw kit and replaced the rubber feet. New SSD and kept the WD 500gb I threw in there like 5 years ago for a mixed drive setup. Added 8GB of new Crucial Ram from the 4GB. Redoing my home theater and media so its being used as a server mainly for plex right now etc. Night and day difference, like a new computer. Yeah the Retina screen is better but as far as speed and and everything else basically no difference. I use Chrome a lot sometimes usually with multiple tabs open and two browsers etc, helped immensely with speed and page outs stay at 0. This is my warhorse, has survived the battlefield. Dogs have knocked it off a table, big water cup spilled on it when they were chasing each other and caught the power cord which in turn caught the cup (flipped upside down and stuck in bag of rice and somehow still works years later lol, even the keys still light up except the right side is fainter), its been dropped and scratched, lid as a dent that somehow didn't crack the screen it bears many scratches from its war wounds. Yet still solid and runs fine. If anything almost think its built better, I've gone through 3 Retinas two of which were replacements under warranty and has me hesitant to buy another as wanted to get a new 13" Pro since the 15" I rarely use as I have my desktop. Was wondering though, ok so we know how if you remove the battery the system runs at half speed with Apple. However I think that also applies when the battery is going bad which I haven't really seen mention of. B/c I did the other stuff then the battery last as waited for shipped on Prime. Computer still seemed slow with all the other upgrades, however new battery and it was kicking again. Wonder if Apples throttling back crap also applies with the battery still in vs out.