I'm using a Windows 11 PC with Bitdefender Antivirus and Mullvad VPN on a 1 Gbps fiber connection. For the past few weeks, Chrome, Edge, and Firefox have all been unusually slow when loading web content. For example, Gmail and the Edge start page can take 10–15 seconds to appear, even though the internet works normally on other devices in the household.
Changing the DNS server on my network connection didn't help. The strange part is that enabling Mullvad VPN immediately fixes the problem—Gmail loads in roughly a second and browsing feels normal again.
I'd like to compare what happens when loading a page with the VPN disabled versus enabled, perhaps using traceroute or another network diagnostic. I'm also wondering whether this behavior could indicate malware or a conflict involving Bitdefender or another network filter.
2 Answers
It may be worth checking for a security-software conflict. Bitdefender can sometimes enable or install VPN-related components, and antivirus web protection or network filtering can interfere with browser traffic. Check that no Bitdefender VPN or duplicate web-protection component is still installed, then temporarily test with Bitdefender’s web/network scanning features disabled. If the browsers immediately speed up, you’ve probably found the cause.
I’ve seen very similar behavior where every browser becomes unusable while other internet applications continue working normally. In that situation, speed tests and apps such as Discord still work, but pages, videos, and streams stall. Since a VPN changes the route and the network path, the issue may involve browser traffic filtering, a local network driver, or the connection path used without the VPN rather than the broadband speed itself. Comparing browser behavior with security filtering disabled and checking the VPN’s connection logs may be more useful than changing DNS again.
I checked Bitdefender and had already uninstalled its VPN previously. Bitdefender is the only security software installed, so I’ll investigate whether one of its web or network protection features is causing the delay.