query-filter: Optimize for SimpleQuery

Before this commit, the QueryFilter used a very naive implementation
where it would just re-filter all contacts if something change (like a
query string). This wasn't of course the most performant thing to do,
and after some investigation we found out that on each search bar
change, we were using quite some CPU.

This commit adds some optimizations by avoiding unnecessary refiltering
of contacts where possible. This shaves off quite a few percentages of
CPU usage when doing some searching in the side bar.

0 files changed, 0 insertions, 0 deletions