Wikipedia
XFast is a lightweight desktop environment that incorporates a display manager and a window manager within the same process. It is portable and works on many devices (embedded devices, handhelds, set-top boxes,...). Here the communication between server layer and desktop layer can be made in classical way via TCP/IP but depending on the configuration and target system it can be done via shared memory too.
The goal of project XFast is to have a very slim and fast graphical environment that contains both within the same project: a replacement for an X-server to give access to the graphics hardware and a WindowManager-like layer that offers user interface elements for applications and desktop management.
Target systems for XFast are (not only) embedded systems with low resources where it is important to have a UI available with short loading times and low memory consumption. It currently runs at Linux, Windows, PlayStation, GP2X and others.
Within the XFast windowing system environment GTK and Simple DirectMedia Layer applications are supported, so there is no need to re-write them. To use them special patched GTK and SDL versions are required, the related patch and build scripts are part of the XFast package. Beside of that XFast offers an own GUI widget library that can be used to write native applications for that windowing system.
XFast is free software that was licensed under the GPL.