SOLUTION
After changing multiple different machines, Windows and SQL versions, I finally manage to discover what was the source of my problem.
Long story short, it was all about the Windows authentication.
On the first picture, I used Windows authentication and the connection was very slow, but once I changed it to the SQL Server Authentication and entered credentials which I set up during the installation process, all those lag/delay issues were gone.
At that time, I've started digging what could be the problem. Finally, the solution was:
- open this file in notepad/notepad++ as an ADMINISTRATOR C:\Windows\System32\drivers\etc
- add this line 127.0.0.1 KRISTIJAN-TRLEN but replace this ** KRISTIJAN-TRLEN** with your SQL server name. You can check your SQL server name by executing this query SELECT @@SERVERNAME
After adding this line, everything was working smoothly