To just open this website I had to change my DNS to point to my router, because the website wouldn't load.
Please take a look at the images below. The first one is with pihole on and the second one is with pihole off.
And this is not the only issue. Websites are loading slowly most of the time (GitHub, Reddit, Google, etc..).
It doesn't matter if I have 1 domain or 3M domains on my list, the issue is the same. No one on my network uses Pihole (it is running locally on my PC through Docker) and they never have this kind of issue.
And please don't tell me there is no way Pihole can cause this because you can see in the images below that it can, I just have no idea why.
It also happens when I disable blocking in PiHole but I leave my DNS to point to it.
I've read that Docker on macOS is inherently slow. For example here is an article about it, with some suggestions for improvement.
With many kinds of applications this wouldn't be so noticeable, but with your system DNS, especially one which is logging to the virtual filesystem, this could feasibly impact throughput. There's no reason why one DNS system or another should affect throughput to a server on the internet per se, which is why it feels like what you're seeing with Pi-hole is a symptom, not a cause.
Some things you might try to see how it affects performance,
That article has some improvements, in particular around the filesystem. There's an article here saying how it's much better out of the box on macOS now, so this depends on how old and in place your setup is.
Temporarily disable logging in Pi-hole (Settings > Privacy > Anonymous mode). Does this change the results?
Are you able to try running Pi-hole on a Raspberry Pi, instead of in a Docker container on macOS? This will confirm no issues with Pi-hole on your network and help confirm or disprove Docker on macOS as the issue. You can export and import lists and rules in Settings > Teleporter.
Are you able to verify if those test's were to the same target IP?
DNS would only be involved in determining the speedtest domain's IP address.
By itself, it has has absolutely no impact on download speeds - once that IP address is known, the download communication is via that IP.
However, depending on your choice of upstreams for Pi-hole, an upstream DNS server may provide a different IP address for the speedtest's domains - you may end up with a target IP that is located further away from you, negatively impacting download speeds.
This would then highlight an issue of the speedtest's fragility, rather than DNS actually slowing down download speeds.
Since you also observe slow website loads, that may indicate a different issue:
Could you upload a fresh debug token? Your original one has expired.
