An out-of-memory error in typically occurs because the game is a 32-bit application that cannot utilize more than 2 GB or 3 GB of RAM by default, causing it to crash during large battles or long matches regardless of your actual system memory.
Go to the tab and click Change... under Virtual Memory. cossacks+3+out+of+memory+work
Units in Cossacks 3 are sprites. Thousands of sprites consume both System RAM and Video RAM (VRAM). If your GPU runs out of VRAM, it starts dumping textures into system RAM, filling the 4GB limit faster. An out-of-memory error in typically occurs because the
To disable it temporarily while playing: cossacks+3+out+of+memory+work