Why is my internet running so slow??

The sticky thing with WIFI is that there are so many possibilities of why it is running slow. The most common reason is interference. This article here explains all possible sources of interference:
http://support.apple.com/kb/HT1365

Another reason also is the type of encryption. Apple recommends I believe a WPA2 encryption, it is a lot more faster (so they say, I have not experienced it really)

Hi Alex.

Don't quite know where WIFI came from (previous post) The fact that your Internet runs faster on one comp. against another, is irrelevant. You didn't say which OS you're running, but it's usually a processor issue. If you're using Safari, you could empty the cache and Reset, but generally, if it's working for everything else, leave it alone.

I've been experiencing a similar problem. I recently bought a new MacBook Black. The new 2.4 GHz Intel Core 2 Duo processor, 250 GB Hard Drive, etc. I connected my old MacBack which had Mac OSX 10.5.3 and transferred all of the stuff to my new MacBook that has Mac OSX 10.5.4 Well, when I first purchased the new Mac, I didn't have any problems with it. Everything was running well. Just recently about 4 or 5 days ago, I noticed that my web browsers were running slower than they usually do. Pages weren't coming up as fast as they used to. I was connected to the internet via a Wireless Router. Well, I turned off Airport and then connected an ethernet connection directly to the Mac and noticed no change. It was still running slowly. So then I checked my old MacBook and noticed it started to the same thing on that one as well. So I'm wondering, is it my MacBook or is it my router?

Oh yeah, I've tried clearing my cache, cookies, and etc. Still no change.

Ok this is strange. Some time after I wrote this post, and not having done anything to my computer or my router, the speed went back to normal. I don't know what exactly happened but again I say, now the speed of my internet has sped back up to normal.