Why in OS X Mavericks internet is so slow?

I have exactly the same problem. Mine is a late 2010 iMac. My router is fine, my iPhone, iPad, Macbook Air, Apple TV and Xbox are all fine, it's just my iMac which is ridiculously slow at browsing and downloading.

PLEASE HELP APPLE.

I am also experiencing periods of very slow wifi performance. Other computers and devices on my network are unaffected. I find that with Safari and Firefox, DNS lookup times out. I changed my DNS servers from google to opendns and the performance improved for a few minutes. Later in the same session, the internet became very slow, and eventually unusable. DNS lookup was failing again. I have found that rebooting the machine allows the internet to function normally for a few minutes, but the problem returns. Help.

2012 rMBP15

That's odd...

What browser(s) are you using?

Are you within good range of the wifi?

It is very odd. I am in the same room as the router, approximately 10 feet away with direct line of sight. I am using Firefox, but the issue shows in Safari and my virtual machines. I am thinking it is a DNS bug issue within Mavericks. The only change in my set up is Mavericks. My other machines, phones, and iPad behave fine.

I'm the same. My only change is Mavericks. My Macbook Air can be in the same room as my iMac and still perform consistently better than the iMac on the internet. Speedtest.net is reporting a difference of up to 15Mbps between my iMac and Macbook Air.

The problem happens on both Safari and Chrome for me. Not tried any other browsers.

Safari has a weird issue with page load times, never could figure it out, so I just stopped using it.

Did you upgrade or install fresh? (if the first, see what happens with a fresh installation)

I run my own DNS on my network, and I also use Google/Sprint DNS, so in a nutshell, my browsing speed is maxed out, the only way to make the network run faster is for the techs upgrade the servers/websites on the other end of the wire.

Imagine, pressing enter and the page is loaded, that is how fast Mavericks runs on my computer.

Try some nslookup commands in terminal, time how long it takes to get a response/IP address (anything less than 3-5 seconds is normal)

nslookup apple.com

nslookup cnn.com

nslookup lifehacker.com

Let me know if you get NXdomain or no server found errors.

I am also experiencing the same problem as everyone else has noted. I have a one-year old MacBook Air. My internet is very slow in both Mail and Safari. Sometimes it can be corrected after a restart but then it will occur again later. Help please.

I have the same problem here with my iMac2010, before upgrading to Mavericks, everything is fine, but now it's very slow and always crash while surfing on the net. This problem not happening on my Mac mini and my other mac with Mountain Lion.

Yes, having the same issue with mavericks. DNS lookup fails at times. iOS devices work fine. Any suggestions?

Web Page Load Times - Slow

Web Page Load Times - Slow (2)

Check in the System Prefereces to see what DNS servers you're using? I use Open DNS servers and they work fine with Mavericks:

OT

I have the same issue and opened a new thread https://discussions.apple.com/thread/5570673.

The problem I found so far

1. arp resolution and icmp stop working, so you will reach 'network unreachable' state eventually

2. local dns service/helper stop working, while dns server is reachable and response correctly

Disabling then enabling network connection will remedy the issue, but the good state is short life.

I'm having the exact same problem. All devices working well except MacBookPro with MacOS mavericks installed. Very frequently addresses everywhere, over terminal, mail client, browser are not reachable. So it's definitely system-wide. Sometimes I'm sensing IP addresses may work whereas domain names don't. Sometime even both aren't working.

Is it possibly a Wi-Fi issue? I connected with a network cable and the problem seemed gone, not a solution though.

Try using a DNS server outside of your home network

Google's is 8.8.8.8

System Preferences > Network

I am on Mavericks and everything on wifi/network is working perfectly.