Why is my Macbook so slow, loud & hot even after upgrades?

I upgraded my Macbook a bit over a year ago with a Crucial m4 256 gb SSD, plus 8 gb of RAM compared to the old 250 gb hard drive and 2 gb of RAM. The extra RAM was just for some apps and games, and the SSD was supposed to make the computer silent and cool. At first the system improved a lot, from startup times to overall performance, but ever since this summer, and especially this fall after upgrading to Mavericks, the performance has slumped quite drastically (might even be worse than before the upgrades). Also, there seems to be a lot more RAM usage than there used to be, although I hardly ever run more than two applications at once (iTunes and Google Chrome). Is it the processor (2.4 gigahertz Intel Core 2 Duo), the new RAM, the new SSD, or the new OS/other programs?