It's a problem with the NVIDIA drivers for 10.13.3 (156/157)! If you install the 10.13.2 drivers (106) using the backwards compatible tool linked below, then everything goes back to normal. No Lag.
Driver versions can be found here:
https://www.tonymacx86.com/nvidia-drivers/
1. Install the latest driver (156/157)
2. Use the `Webdriver All Versions.app` to install 106 driver
- If you need a DL link for the app, here it is
https://drive.google.com/open?id=1hI4dqVZ621fPeKR6YFoLFQGD-ciiZ3xO
- Open the app, choose „Webdriver neu installieren“ („Reinstall web driver“), choose the old webdriver *.pkg file – the app installs the old driver.
3. Restart the app
4. choose „Vorhandenen Webdriver Patchen“ („patch existing web driver“)
– click through, choose „Rechte bereinigen“ („correct permissions“) enter admin password
5. Reboot using the button on the app (takes a few moments)
Credit to:
https://www.tonymacx86.com/threads/macos-10-13-3-update.243852/page-13#post-1677090