Don't search until the query is ready (don't trigger searching more frequently than the user can type)
Searching in GNOME Software is expensive both for the backend and the frontend, and doing this every 150ms is very wasteful (think in terms of CPU + graphics + power consumption + mobile) because nobody can think and type that fast (and I can mathematically prove it).
Same principles and logic as gnome-calendar#1170 (closed), https://github.com/getting-things-gnome/gtg/issues/281, GNOME/Incubator/papers#101 (closed), etc.
I will provide a patch for this, as I have tested with the GtkInspector and found that change to be an effective performance improvement for GNOME Software in practice.