Pi-hole Slowness – High Query Latency, Slow Dashboard, and DNS Delays on Pi Zero

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Expected Behaviour:

Pi-hole should respond quickly to DNS queries, the admin dashboard should load promptly, and network devices should not experience delays in page loads or DNS resolution.

  • Operating System: Raspberry Pi OS Lite
  • Hardware: Raspberry Pi Zero W 2 (512MB RAM)
  • Pi-hole is the primary DNS resolver for the LAN (192.168.5.253)
  • Acting as a Tailscale subnet router
  • Upstream DNS set to Cloudflare (1.1.1.1)
  • Logging is disabled
  • Adlists are minimal (gravity.db is 7.8MB)
  • Very few or no regex filters
  • Home Assistant is running separately on a Windows home server with multiple internet-using integrations (e.g., weather, Google, Nanit, etc.)
  • Approximately 28 clients on the network

Actual Behaviour:

  • DNS queries are slow, even when blocking is disabled
  • Browsing between pages on the same website causes delays
  • The Pi-hole dashboard is slow to load (5–10 seconds)
  • Clicking actions like “Enable Blocking” takes several seconds to complete
  • SSH into the Pi-hole sometimes takes a few seconds to connect
  • pihole-FTL uses ~130MB RAM
  • Swap usage is around 140MB
  • I/O wait is ~1–2%
  • The issue started recently with no major changes to the setup

I’ve already tried:

  • Disabling logging
  • Restarting DNS and rebooting
  • Reducing Home Assistant integration polling
  • Cleaning up adlists

Debug Token:

https://tricorder.pi-hole.net/PqXyd2wp/

2

Pihole 6 (upgraded from v5) was running slow on my Pi 3. Searching around the net the solution was to reduce the size of the FTL database. I followed this guide which resolved the issue.

Granted you lose the history but it was much better than slow device.

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