Extremely slow on web target platform

Describe the Bug

When using the library, the UI is very slow in responding (esp. after log-in until next page shows up), if compiled to web platform.
I can expect some performance loss due to JS, but this is not that simple. It's very stably slow, especially when looking at the Network tab in developer tool -- there is a very stable delay between every two requests of a Solid resource.

A wild guess is that the part for calculating authorization headers takes the time, due to cryptographic calculations.

To Reproduce

Steps to reproduce the behavior:
0. Compile to web target, and launch the instance (e.g. flutter run -d web-server)

1. Go to the log-in page
2. Click on log-in
   1. Optionally open the developer console at this time, and switch to Network tab
3. Finish log-in on the new window
4. You can see how long it takes for the "waiting for log-in animation" to disappear and the next page shows up

Screenshots

Screenshot of Network tab of DevTool, after logging-in on the other window

Desktop (please complete the following information):

• Linux
• macOS

Doesn't really matter, as it's for web target. So:

• firefox
• chromium
• chrome

Additional Context

I'm using v0.6.12, as I haven't managed to upgrade to v0.7.x, due to some internal changes breaking my app. Hopefully there can be a clear document for breaking changes and alternatives / migration path, so I can try the new version to see if it improves.

Same experience on v0.7.6.