• Firstly, find w2.exe in your game folder.
  It is located in Steam/steamapps/common/WormsWorldParty/
  
• Then, click right mouse button on w2.exe and select Properties
  
• Choose Compatibility and tick Disable fullscreen optimizations to fix your lags
  
  
• Tadam, it's fixed ;)

I hope that my guide helped you :)
If you have any questions feel free to write them in the comments section.