Sujet : [Patch 3.15] Borderless Windowed mode causes frame rate drop in outside videos

First I load FFXIV in borderless window mode. Then I start playing a video in youtube / windows media player, and now all videos drop to 5-10 frames per second whenever FFXIV application has focus. If I take focus away from FFXIV the frame returns to normal, and I've never had this issue till this week.

1) I'm not sure is this is as a result of the recent FFXIV patch or the recent Windows 10 patch.

2) If I set FFXIV application to Windowed or Full Screen mode the issue does not exist. It only exists in Borderless Windowed mode.

3) I have tested this with other games and have not been able to repeat the issue.

Edit: This is a dual-screen setup