Some troubleshooting ideas:
- Before using the macro, "Cancel All Macros" in the KM Status menu
- Check the Mac "Activity Monitor" app to see if there are any apps/processes using excessive CPU.
- Try the typed string macro in an app you know responds well, like BBEdit or TextWrangler.
- Restart the KM Engine
- If all else fails, restart your Mac.
You can also check the Troubleshooting [Keyboard Maestro Wiki] article. I didn't see anything relevant, but maybe you might spot something.
Good luck, and let us know how it goes.