[enhancement] reduce startup time

[mattia-b89]

Startup of the service requires much time: more than 3 secs, far more than any other service, like tracker or pulseaudio:

[mattia@arch-xps ~]$ systemd-analyze blame --user
          3.051s org.gnome.GPaste.service
           282ms tracker-store.service
           273ms pulseaudio.service
[...]

I think is an issue worth to be examined

[Keruspe]

Startup time depends on the size of your history. How many items are there in your history?

[mattia-b89]

Default settings, 1000 elements in history

[Keruspe]

Can you run du -h ~/.local/share/gpaste/history.xml ?

Here it weighs 244k and loads in ~300ms

[mattia-b89]

[mattia@arch-xps ~]$ du -h ~/.local/share/gpaste/history.xml
472K	/home/mattia/.local/share/gpaste/history.xml