Firefox starting slow

[cscs]

No … instead remove your bad portal.
(as mentioned in the release announcement and a hundred other threads not 2 years old)
(( you probably have xdg-desktop-portal-gnome installed on a not-gnome desktop. ))

Very long strart of GTK applications

pacman -Qs xdg-desktop-portal-gnome && sudo pacman -Rdd xdg-desktop-portal-gnome && sudo pacman -Syu xdg-desktop-portal-gtk || echo "Its something else!"

@philm

Many applications (firefox, thunderbird, telegram, etc) slow to start on desktops other than Gnome

There is a bug with xdg-desktop-portal-gnome (more details here ).

Workaround for gtk-based desktops (including Xfce)

sudo pacman -Rdd xdg-desktop-portal-gnome
sudo pacman -S xdg-desktop-portal-gtk

Workaround for KDE

sudo pacman -Rdd xdg-desktop-portal-gnome
sudo pacman -S xdg-desktop-portal-kde

Workaround for Lxqt

sudo pacman -Rdd xdg-desktop-portal-gnome
sudo pacman -S xdg-desktop-portal-lxqt