- Making assets embedded as base64 (img src the header logo as base64, all CSS should be inline, etc.).

- Leveraging CSS as much as possible (if you use animations and transitions, use CSS as much as possible for these, avoid JS for them).

- Make sure your website is mostly rendered on the backend. If you're to have JS, your website should work without it.

- Security becomes REALLY fun, as in, avoid XSS, CSRF, SQL Injection attacks and any other injections as much as possible.

As someone summarizes in another comment[0], keep the chattiness as minimal as possible. By chattiness I understand they mean, pack as much data as you can in the same Keep-Alive connection. Avoid making new HTTP requests as much as possible, as each one might get assigned to a new Onion route making things slow.

If you can ship your website to the browser in a single connection, you've won.

I've always been impressed by performance of these big Onion sites, they really push the limits of software engineering creativity, given these constraints and nature of Tor.

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[0]: https://news.ycombinator.com/item?id=49872320

EDIT: Formatting of bullet points.

I wrote about it in 2600 almost ten years ago (already?!). A copy of my article can be found here: https://pablorauzy.fr/outreach/2600/how-to-run-a-tor-hidden-...

If you have an Onion copy of your website, don't forget the Onion-Location http header which will automatically redirect Tor Browser users to the onion version of the website even if they visit it at the clear web address.

If it interests people, I also have a follow up article about I2P: https://pablorauzy.fr/outreach/2600/how-to-run-an-i2p-hidden...

> HiddenServicePort 80 127.13.37.1:8080

> listen 127.13.37.1:8080;

This way, strangers won't be able to connect to a service bound to 127.0.0.1, should you ever decide to re-use the port and forget to disable the hidden service.

You'll also need to use separate ports and/or bind addresses if you host multiple hidden services and don't want people to correlate them - if nginx doesn't match the Host header, it will serve whichever site comes first alphabetically.

1. If you want to improve page load speed you need to buy a HTTPS certificate so you are not limited to HTTP/1.1. Multiplexing in HTTP/2 is important for getting sites to load fast.

2. You can set the HiddenServiceExportCircuitID configuration to pass the circuit id to your web server for telemetry or anti abuse purposes. Otherwise your logs will say that all users are coming from the same IP.

https://blog.cloudflare.com/cloudflare-onion-service