Blutok: have a look at the Beamdog Forums in the troubleshooting section (use 'Long or Slow Save and Transitioning Areas' in search).
For some reason I can't post the link...
Thanks for your help, I've found a solution :)
Here it is (it is not my solution, I've jest copied it from BeamDog forums, all thanks to: Gusinda
"- Download OpenGL32.dll (32Bit) driver, unpack and copy into the root of the game folder (where Baldur.exe lives)
- run the game in OpenGL mode [I've just normally launched it trough gog galaxy - Blutok]
- Test saved game, quicksave and named, and transtion between areas. Hopefully it all runs smoothly!"
AS for me I needed to use 'Alternative Render' mode in graphic options to run the game smoothly after this operation, for now everything works perfect :-)
Link to the beamdog forum topic solving the problem: https://forums.beamdog.com/discussion/72294/bgee-bg2ee-iwdee-long-or-slow-save-and-transitioning-areas-possible-work-around