JabRef 5.0-pull-5945-merge.440--2020-02-19--fcaeef1
Linux 5.4.19-050419-generic amd64
Java 13.0.2

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behavior:

1. Open a large BIB file (say 1000-2000+ entries)
2. You might have to wait up to 2-3 seconds. The issue gets a real one once you have 5-6 files from the last session that altogether form several 1000 entries to be loaded.
3. Type keyword into search field, you might be required to wait a bit after each letter entered

Loading a larger DB (1000+ entries) takes unusually long (even on my i7 8th gen laptop).
JR5 to me shows to be significantly slower than JR3/4, which was faster even on my old machine, an i7 4th gen. This way, search renders to be difficult to use because typed-in letters don't show in the text field before the search procedure has returned.

JabRef 3/4 still had the option to enter the search term and hit enter to start the search.

Hence, it would be highly useful to at least have a switch to toggle between "old-school" and "as-you-type" search.

My observation might be linked to that issue.