JabRef 5.2--2020-12-24--6a2a512
Windows 10 10.0 amd64
Java 14.0.2

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

This issue is present on the v5.2 stable.

Steps to reproduce the behavior:

1. Create a larger file with 3000+ entries
2. Try to save it...

Cannot help myself but it is really disappointing to see JabRef v5.2 still hogged when saving a large(r) library. I have 3000 entries, and whenever I hit Ctrl+S the computer fans start to ramp up and the status of JabRef in Task Manager goes to "Not responding"... This goes on for minutes (approx 5) until things settle (who know what is a problem with saving a txt file)!

This is really upsetting with a stable version, as it makes serious work almost impossible. I am sorry but default CPU usage around 20% on an 8-Core i7 7700HQ - 32GB RAM - 1TB NVMe SSD is just simply unacceptable.