Computers and Web Browsers

I'll apologize in advance if I go way too in-depth about my computer. My roommates commonly think that I'm speaking a foreign language when I talk about my computers, so I know that I have a tendency to not make any sense. But oh well . . . Over Christmas, I got to upgrade my computer to the most up-to-date operating system (software) for Mac (commonly known as Lion). It was a long and painful process (which was my own fault) and we had to erase my entire hard drive to get to that point (also my fault), but I was really excited about it, because I was using really old, out-of-date software.
There are certain things that I like about Lion, compared to Leopard, which was the software that I had before, but there are also certain things that are a pain. For example, my computer runs really slowly on Lion - a problem that I didn't have before. I'm almost positive that I know exactly what the problem is, but it would cost a lot of money to fix it. So that's a little bit annoying. And I've also been playing a game of trying to figure out the best web browser to use, since those behave differently now than they did before. I started with just Safari (the web browser that comes with Mac), but every time I open Safari, I get the rainbow beach ball (the equivalent of the hourglass, for any Windows/PC people). And the rainbow beach ball has to be there for at least 10 seconds before I can do anything. And then I get it every time I have to go to a different page, or open a new tab, etc. It's really slow.
So I decided to try Google Chrome instead, since I like Google Earth, and Chrome comes with Google Earth. Chrome runs a lot faster, usually without the rainbow beach ball. However, it uses up pretty much all of the CPU on my computer and heats the whole thing up. And then my fans start running really fast, and it can get kind of loud. One of my roommates has even commented that it sounds like my computer is dying. I've checked to see what the problem is, and I'm about 100% sure that Chrome is the problem. Everything goes back to normal and my computer gets quiet again when I quit Chrome. Also, Chrome refuses to open my Yahoo email, which is kind of annoying. I have to run that through Safari.
So today I decided that I would try Firefox and see if that's any better. I just reached this decision about five minutes ago, so we'll see how the results are. So far, though, there haven't been any rainbow beach balls, and my computer is fairly quiet. It also opens my Yahoo email, which is a plus. We'll see if that lasts. If it does, then I'll probably get rid of Chrome and just make Firefox my default browser so that I don't have to deal with the annoyances of the other two. So I'm hoping that Firefox will work better.