First off, disable any trackers if using any.
And since you're on PC, this list could be helpful:
Common solution for technical problems (PC):
- For performance issues, try to disable V-Sync.
- Remove all add-ons (GwentUp, Gwent Tracker).
- Remove/disable all third party overlay applications (e.g. FRAPS, RivaTuner).
- Try a verify / repair through GOG Galaxy and ensure Galaxy itself is up to date.
- Install / repair redistributables that come wit the game (DirectX, Visual Studio, etc.).
- Be sure the game is not installed under Program Files or Program Files(x86) and set up the .EXE files of Galaxy and Gwent to "Run as administrator".
- Disable the Galaxy overlay (only for debugging; it should be enabled for buying kegs and inviting friends).
- Disable your virus protection software / firewall.
- Close all background applications, especially Chrome (and other resource-consuming apps).
- If that doesn't work; try to reinstall the game (also removing the game data when asked).
- If this doesn't fix things, run a dxdiag with the 64-bit option selected and send the results to CDPR Support along with a brief description of the issue.