Well something is off for lack of a better way of putting it. Either your sights are not aligned when the shot breaks or you are aimed left. How this is happening must be determined.
Can you describe your presentation? Since you are experiencing your problem "at speed" I'm thinking about how you are getting the gun on target and if you have any extra English on the gun at the end of the presentation that is causing your consistent left problem. You could be verifying your sight alignment before the gun is stopped.
Have you done any Natural Point of Aim dry fire drills? Focus on a point on the target. Begin your presentation. When you acquire a firing grip in the holster close your eyes and finish your presentation. Open your eyes and look where the gun is pointed. You can do a similar drill just by pointing in at the target and closing your eyes and counting to 10. Again open your eyes and see where you are pointing. Are you consistently drifting to the left on the target? You may need to adjust your stance in relation to the target.