Fix DPC Latency – Firewalls, AV, Bonjour

This is an addendum to the original article on this subject – What Is DPC Latency, How To Fix It. For the full skinny on DPC Latency, you should really read that article before continuing with this one.


Firewalls can become a tricky conversation. Even after many years of using them, people still disagree on where and how they should be implemented.

What Is A Firewall

A firewall can come in two forms: hardware, and software. A hardware firewall would be a router that sits between you and the internet. The bad guys on the internet are constantly bombarding you with attempts to get inside your computer. A software firewall is one like the Microsoft Defender Firewall that sits between your router and every other device connected to your local network.

How They Work

Router Protection

Their job is pretty basic, really. If you send a request for a web page, video, or download, for example, your router will make note of this request and also keep track of the particular device that sent the request. When a response returns from the internet, the firewall will recognize it as having been requested and, therefore, accept its delivery to your machine. If it doesn’t have a record of a request being sent, it simply drops the data packet.

Software Protection

Software firewalls will protect you from those who share your LAN like your nasty sibling who doesn’t have a clue about security.

If you don’t share your LAN with anyone and don’t have relatives visiting and using your computer, then it is probably OK to disable your software firewall — your router should suffice. If you use a wireless connection (or have it enabled), then I definitely would keep the software firewall enabled. You never know if a neighbor might have access to your connection although this shouldn’t happen with a strong password in place along with good encryption established.

I don’t make these recommendations lightly. There are many considerations to take into account and my first bit of advice would be to leave firewalls enabled.

Outbound Firewalls

Outbound firewalls monitor all data packets that originate from your computer. If you have been hit with a virus, for example, it might be trying to “call home”. An outbound firewall won’t protect you from this but you will at least be aware of a problem.

Firewall Recommendations

If you are behind a router, then definitely enable its firewall. It is your first line of defense against the ever-burning internet.

If you don’t have wireless enabled and you are the only one using your LAN, disabling your software firewall should be OK. Be aware that the Microsoft Defender Firewall uses very few resources and it doesn’t hurt to leave it running.

Third-Party Firewalls

Third-party firewalls are a whole different kettle of fish. They generally leave a big resource footprint. These programs might be the cause of high DPC latency. You might want to try disabling them to see if your latency problem goes away after doing so.

Third-Party Antivirus

Back when Microsoft Defender was called something else (not always nice things) and wasn’t highly regarded among the tech gurus, I used to be a big fan of third-party antivirus software. Now, not so much.

My biggest problem with these programs is that they tend to be bloated. They are no longer simply devoted to antivirus protection. It would seem the developers are trying to be a one-stop-shop for all your security needs. They want to be antivirus programs, firewalls, browser safety plugins, and God knows what else. They generally are overkill, in my opinion, and can really bring a computer to its knees.

For these reasons, I don’t feel they are warranted and think Microsoft Defender is all you need these days. The resource footprint is light, it is free, and is bundled with Windows 10. It also ranks high on the AV-Test website.

Never Run Two

Never run two AV programs at the same time. They will conflict with each other and can even be the cause of intermittent crashes much less the latency problems they will most likely cause.


If you use or have ever installed any Apple service, like iTunes, then Bonjour is probably running in the background. If you aren’t using any Apple services, then Bonjour is nothing more than dead weight chewing up system resources, and wasting disk space.

Note: I had a friend visit a few years ago and he brought his iPad along with him. Unbeknownst to me, Bonjour was installed on my system. I didn’t discover it for a long time afterward.

If you don’t use it, lose it:

  1. Open Control Panel
  2. Choose Programs and Features
  3. If you see Bonjour listed, uninstall it

After walking you through all of the above, it is time to check that DPC latency again. If the problem no longer exists, then you are done, and congratulations!

If you still have latency troubles, then stay tuned for the next installment of this ongoing set of articles where we’ll be talking about PowerMizer and IPv6.

As always, if you have any helpful suggestions, comments or questions, please share them with us,


2 thoughts on “Fix DPC Latency – Firewalls, AV, Bonjour”

  1. How does Malwarebytes fit into security. I think it slows down my pc especially at boot time.
    I use windows firewall and assume my router firewall is set to on.
    I mainly connect using ethernet and only turn wifi on when needed for a particular reason but often forget to turn wifi off again until I notice it is still running.
    Look forward to views on this. Barry

    1. Richard Pedersen

      Hi Barry,

      If you use the free version of MBAM, then there is no reason to run it at boot time. This can be checked in Task Manager in the Startup tab.

      To check if the Windows Firewall is active, do this:

      1. Use the Windows key + I to open Settings
      2. Choose Update & Security
      3. Choose Windows Security

      The entry labeled Firewall & Network protection should be checked if it is enabled.

      I can’t help you with the WiFi problem 😉

      Hope this helps,

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