When cheching my network’s the Zigbee Settings hidden menu, I noticed 2599 entries, which does not sound normal. Could that cause issue? Can that list be cleaned up somehow (seems to be in the Conf table of the DB)?
And another issue with his database Issue: Deconz becomes unresponsive when using DDF for Tuya TS011F Plugs - #28 by iisworks
The database is filled with many lines whith the same sid (and it s the primary key)
No, the other issue is mine as well. But this take does not have duplicate primary keys conflict. I was just wondering… 
Yeah I know, but 2 databases possibles issues on the same user …
You have restarted from a new one or was the same database for both issue ?
For information you have a new entry on this database every time you change something, and on your capture you are switching deconz version, so it’s possible it’s normal (but why you have switched your deconz version 2599 time ? ^^)
And at a certain point there were 2500 identical entries. Anyway, I ended up starting with an empty database, spent half a day pairing my 40 devices. That did not go too well btw. Especially Aqara motion and Temp sensors were problematic. Some of them paired in seconds, in other cases I ended up with a device with a weird subsensor name and a partial Basic cluster (16/18 instead of 32?) and like 10 separate orphaned subdevices in deconz. Sometimes after a deconz restart they got merged to one functional device?
I had to restart, remove, repair etc. many times before everything was paired expected. A lot of trial and error, not a smooth experience. 
But at least the DB is now very small: 228KB (previous one wat 1.3MB).
That many entries is indeed unusual, I recon this might have happened in an older deCONZ version. The mechanism to add a new entry is relative simple, if some network/version parameter changes a new entry is added.