The problem seems to be related to having open too many wallets.
I had 7 wallets open and the sync was way tow slow. 3-4days for a complete resync.
Now I have closed all wallets but one and restarted the client. Now it has alread synced 1/3 in only 10 minutes!
Hope this helps someone, and please excuse my message to this old thread.
That's good advice.
It's one of the reasons why we moved away from the 'all wallets open' in Classic and introduced 'switch wallet' in HD.