My game is flickering
Try lowering the game resolution. Run the configtool.exe file in the install folder (in the Steam library, right click on the game and select Properties, switch to the Local Files tab, click the 'Browse Local Files...' button).
Try the Windows 8 Performance "Patch" (works in Win 7 and 10, as well).
In the ..\SteamApps\common\divine_divinity install folder, try right clicking on the div.exe program file, select Properties, switch to the Compatibility tab and try different compatibility modes. In Win 7, disable desktop composition and check 'Disable display scaling on high DPI settings'; for Win 10, check 'Override high DPI scaling behavior' (set it to Application) and maybe uncheck fullscreen optimization.
You can try using the disk version of the configuration program, to set the game to run in Direct Draw mode. Rename or move the existing configtool.exe and NlsEng.dll files in the install folder, and extract the disk versions from this zip file.
Note that this will also reset the game resolution to what the disk version supported, but you can manually edit the config.div file in a text editor to change the resolution back.
Try the 4GB Patch to increase the amount of virtual memory that the game (or any 32 bit application) can access in 64 bit versions of Windows.