The libxmlb library is much faster to load and query as it does not require
the client to parse all the XML metadata at startup. It's a zero-copy mmap
design that is more modern and less clunky. In case of memory pressure on low
RAM machines, the compressed XML is evicted from memory and automatically
reloaded when required.

For a single operation, startup time has decreased by 40%, and RSS usage is
down by a massive 78%. The GUI process has similar wins, with a reduction in
startup time by 13% and RSS usage is down by 45%. This now means the idle
process uses less than 50Mb with all plugins enabled.