It's been a couple of weeks now that I feel that my pc is feeling slower than usual. Not just network related things but just about everything gets a delay (timings at the end of the post). It's like my IO decides to take a nap until the next reboot.

I couldn't really pinpoint what was causing the issue until I restarted my laptop with the hardware switch to turn off the wifi off in it's off state. Suddenly the machine is working at it's full speed again! Sure though once I turned wifi back on everything slowed down again. Even enabling wifi adapter without connecting to any network slows everything down.

A person would think that switching the adapter back to off disabling the adapter would fix the problem again but no luck there. The only fix to have the system run fast again is to reboot the system with the hardware switch off.

Even when I work offline without any connection whatsoever the pc stays slower...

One other thing I noticed is that when my AC adapter isn't plugged in the pc seems to go faster again (on balanced and high performance power setting) which completely makes no sense :/

My laptop is mainly connected using gigabit connection to the company network but I also make a wireless connection to reroute all the internet traffic through the wireless network.

Things I already checked/changed/tested:

  • renew all adapters (either using ipconfig or by pulling out cable)
  • Disabled bluetooth adapter during all the tests
  • Updated the network adapter drivers to their latest version
  • The routing table is identical before enabling / after re-disabling the wifi adapter

My system consists out (relevant items):

  • Dell Latitude E6520 Running Windows 7 64 bit
  • Wireless network card: Intel centrino advanced-n 6235 (driver v:
  • Wired network card: Intel(R) 82579LM Gigabit Network Connection (driver v:

So if anyone can point me in the direction on what this could be caused by that would be a big help!

Testing results (all averaged from 3 trials):

Starting current developing app from visual studio  
Before Wifi on:   4.4 sec  
After Wifi on:   14.7 sec 

Starting Windows Explorer
Before Wifi on:   0.4 sec  
After Wifi on:    1.3 sec 

Going to lockscreen
Before Wifi on:   0.4 sec  
After Wifi on:    1.5 sec 

Network connectivity before Wifi on: enter image description here After wifi was turned on: enter image description here

  • How can you be connected if WiFi was disabled??
    – Ramhound
    Commented Sep 3, 2013 at 15:57
  • Forgot to mention, I connect using ethernet gigabit and wifi, updated my question.
    – Stormenet
    Commented Sep 3, 2013 at 16:37
  • Your wire connection would not result in a wireless connection to those devices. How many WiFi adpators do you have installed? A wired connection would NOT have a signal stregth. It sounds like you have hardware that is causing the problem, using an external adaptor, might solve your problem. I have seen nothing but problems with the Intel Centrino adapator in every device I have worked with one.
    – Ramhound
    Commented Sep 3, 2013 at 17:36
  • Those devices are other devices in the wired network and the test I am running is a tool form the Incredibuild build helper to test the connection speed to other build helpers in the network, it has nothing to do with the wireless connection ;)
    – Stormenet
    Commented Sep 4, 2013 at 6:46
  • Anyway, problem solved, see my answer.
    – Stormenet
    Commented Sep 4, 2013 at 7:47

2 Answers 2


Okay, ultimately when I did some more tests with AC adapter in and out it felt strange that the laptop ran faster again with the AC adapter out.

When I tested with another Dell adapter the laptop ran it's normal speed again. How the wifi hardware switch is connected in this story, I don't know, probably some electronics story there.

The old AC adapter: LA65NS0-00 19.5 V - 3.34 A
The new AC adapter: FA90PM111 19.5 V - 4.62 A

So if you also have the issue that your pc is running slow mysteriously and you have a Dell PC, check your adapter first, maybe it isn't powerful enough or the detection pin is broken (Dell AC adapter has a logic/signature pin, you can see it in the middle of the plug). My story is that I received a wrong adapter from the IT department.

  • Its pretty clear. Your laptop requires more then 3.34A to work. When your AC adapter is plugged in your battery is disconnect or placed into a mode so it can be charged. This means all power requirements must come from the adapater itself. My guess you confused the adapters you were using with a different laptop.
    – Ramhound
    Commented Sep 4, 2013 at 12:12

I am having the same slow computer issue with my Lenovo ThinkPad L512 (11/02) running Windows 7 Pro. It runs so slow that it takes 1-2 min to move the cursor from A to B instead of a fraction of a second. I CCleaned everything and shut down all open webpages, and reboot to no avail. The laptop will act normal if I switch off the Wi-Fi (a physical Wi-Fi switch on the right side of the laptop) or unplug the Wi-Fi card. The failing Wi-Fi card is FRU P/N: 43Y6553 Realtek RTL8191SE Wireless b/g/n Card. I am looking at this failing Wi-Fi card now and see a replacement date I wrote on it: 8/2018.

So I am right now using Wi-Fi through a USB Wi-Fi dongle for internet connection. Everything works perfectly the way it should be. After reading this post, I did a little experiment with battery and wall charger. The cursor moving speed: just wall charger > just battery > wall charger + battery. The failing battery is in the way.

The verdict is that the failing Wi-Fi card slows my Lenovo ThinkPad L512 to a crawl. The failing battery doesn't help either.


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