This is an essential addon for the internet plague of white or light backgrounds. Unfortunately it stops multi threading and makes all the browsers that I have tried it on crawl to a stop with mind numbingly slow page load times.

I am currently using Cyberfox 52.9.1 with DBLT v0.6.8 the highest supported version. I prefer v0.5.14 because it allows the backgrounds of mozilla and addons pages to be altered but I thought that I would test with the latest supported version to see if multithreading would work, which it does not. No other addons installed so nothing else to blame but DBLT. Help->Troubleshooting Info shows whether multithreading is enabled/disabled.