All of them speeding up the fetching of tiles in two ways.
- By downloading a service file telling us where third-party tile servers are instead of using redirect by proxy
- Allowing for more consecutive HTTP requests
Once your distro of choice picks up one of these stable releases you should be back to at least the old Mapquest speed of Maps. And if your distro upgrades to latest libchamplain when it arrives you will see even greater speeds.
And as a bonus, the latest libchamplain release will bring horizontal map wrapping, courtesy of excellent GSoC student Marius Stanciu!