My MacBook Pro runs really slow sometimes

I got this Macbook Pro back in late October. It's the brand new version with 250 hard drive and 4g memory.

Lately, safari has been running really slow all of a sudden, but it doesn't always do this. Sometimes it works just fine, sometimes it works at an average speed, but sometimes it takes like 5 minutes to load up youtube or facebook or any other sites. I recently downloaded Firefox but I don't think it helped much.

I'm totally new to Macs and I don't know what to do. I don't know if it has a virus or what. Is there anyway to fix this?

Thanks in advance.

More then likely it's not a virus or your computer. Have you checked to make sure you're getting full access to your wireless internet? Also go to Applications > Utilities > Disk Utility > select your drive and then press verify/repair disk permissions to clean up some junk so to speak. Also you can download iceclean or onyx to do some basic cleaning all over your computer.

Adding to that... facebook is notorious for slow loading, faulty loading, and any other form of site overload glitches.
I good way to test this is for instance opening this site when you are having problems loading facebook , and making sure that it's not just Facebook playing up (AGAIN).
As for the other sites, if it is something that only started happening recently, go with the above advice, as I am guessing that you have just let your caches, etc get a bit full, and your disk permissions may be running amok.

I'm going to guess your on a wireless network, and if you were to ping your router, you would see many dropped packets, as well as many packets that take very long to be returned.

That or its just your ISP blows.

This is what I do to speed up Safari:
- Click on "Safari" and click on "Private Browsing". Make sure it is turned off.
- Click on "Safari" and click on "Reset Safari". From there, tick the boxes that you want to clear. For me, I tick history, cache, downloads, cookies, website icons, autofill and Close Safari window then click reset and Safari will restart back up.