Slow iMac Internet/Networking Connection

Discussion in 'iMac' started by mikek836, Apr 4, 2011.

  1. mikek836 macrumors newbie

    Apr 4, 2011
    Houston, TX
    Hello, I'm having some issues with my iMac I can't seem to figure out. Here are the specs:

    27" iMac 2.8 GHz Core i7
    8 GB 1067 MHz DDR3 RAM
    1 TB 7200 rpm HD
    Networked via GB Ethernet connection
    Use Safari for most browsing (v 5.0.3)

    Over the past few months, I've noticed the networking performance on my machine has been considerably slower than when I bought it. Internet pages take much longer to load, streaming video is basically out of the question at this point, and my Time Machine backups to my Time Capsule were taking much longer than they used to. The first thing that I noticed is that my Time Machine icon seemed to be perpetually spinning and indicated it was indexing the backup. I'd heard that the Time Capsule's performance can sometimes be affected by being in an enclosed space due to heat, so I moved mine to a more open area to where it could breath more effectively. When that didn't help, I stopped automatic backups to see if that would help. It did nothing for me either. I've created a new user account to test to see if that would help, and I'm experiencing the same issue. I tried quitting every application that uses an internet connection except for Safari, and that didn't help either.

    My system shows almost no network traffic any time I'm on it, and activity monitor shows almost no processor usage either. The rest of my system is still fast when opening windows and applications and such. I also don't think it's my internet connection, as I had a MBP for work that I use at home from time to time and the internet connection on it works flawlessly.

    This leads me to believe there is some kind of virus/spyware on my machine that's slowing it down. I installed Sophos and it's been running; it found and killed JS/WndRedB, but that hasn't helped either. The only other oddity I've found is the amount of data sent. I've had my computer on for about 11 days straight now, and in that time, I've received a little over 2 GB of data but have sent out almost 12 GB. I find it hard to believe that I as a user have actually needed to send out that much data.

    Any suggestions would be appreciated, and let me know if you need any more information.

  2. macabouttobe macrumors regular


    Aug 5, 2007
    I noticed an issue with web pages loading really slow, pausing, stuttering, you name it when I first got my iMac. I did some research and it appears to be related to the DNS service with my ISP. I have AT&T Uverse (love it) and fornwhatever reason the DNS Services (maybe the way the 2wire router communicates) or whatever doesn't work too well on iMacs.

    I found an awesome work-around with OpenDNS. Immediate improvement, and depending on your router you can manually enter their DNS addresses into your router. Check them out at and give it a try, they have tons of documentation on how to do it.

    I have no option to change my DNS settings on my router (due to the fact they route my TV and Phone so I don't blame them for dimming out that option). I manually changed my DNS Settings on my computer and they have a slick little "widget" that chases around my changing dynamic IP Address because I use it as my content filter that you can customize (young kids and I can block undesirable things). It's free. I haven't had to go to their website in a couple years and it appears they still have a free version. I don't recall it saying "ad supported" in the past and I've never seen an Ad so I don't know how that impacts things. For a proof on concept you can enter their DNS addresses into your computer and go start surfing around to see if that is indeed your issue. Undo it and it goes away. There are probably other services out there, but AT&T's DNS services I guess have a reputation for slowing down your Mac's internet surfing (not thru-put).

    Good Luck!
  3. GGJstudios macrumors Westmere


    May 16, 2008
    There has never been a virus in the wild that runs on Mac OS X. The handful of trojans that exist can be easily avoided with some education and common sense and care in what software you install:
    WndRedB is a Windows trojan. It can't affect Mac OS X.
  4. Drewbie macrumors member

    Aug 27, 2010
    pull the system config folder to completely reset your network preferences
    /library/preferences/system configuration
    move that to desktop/trash

    then go into keychain access and delete any keychain entries that have your network name and airport network password as the kind.

    then i would reboot the system and reconnect

    if that doesn't work then i would indeed add in manual DNS servers to network preferences, or better yet have the router take care of them
  5. mikek836 thread starter macrumors newbie

    Apr 4, 2011
    Houston, TX
    Thanks for the suggestions. I do have a question though: given that my MBP runs on the same network as my iMac, it stands to reason it's using the same DNS servers, and its connection and internet speed are flawless over Wi-Fi. The other thing that the DNS fix doesn't explain for me is why my machine is sending out GB of data that I can't for the life of me figure out what it is? Any ideas on what could cause this?

    I'm using a Linksys RVS4000 router, and I went to log in to the router set up. It took over 5 minutes for the setup page to load on my iMac; every other time I've logged into a router, it's nearly instantaneous. Figured this was a little strange as well.

    Again, thanks for your help, and any other suggestions are appreciated.


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