Autocomplete hangs apps for a few seconds


I have an odd issue where applications such as Pamac and Opera hang for a few seconds after typing 3 characters in the search / address bar before showing autocomplete options.
It does not occur with Firefox which immediately drops down the autocomplete options when the address bar gets focus.
I have tried on a clean installation without any themes.
This only occurs when trying in the search bar the first time the application loads. Subsequent searches work fine.

Any idea what could be causing this?

Thank you

Cache loading? This is likely relevant to applications individually.
(The application creates a cache on startup or at the first use of the feature. The first use may thus be slower than subsequent ones, when the cache is entirely built.)