Weird recording problem since I upgraded to Windows 10

[Nidale]

Problem happens for both recording and streaming. Tried in OBS and Xsplit. Before windows 10 I had no problem. Since streaming is another level, let's just talk about the recording problem.

My problem is everything I record has lag in it, BUT only when I'm actually using the screen, when I put my mouse and click on my 2nd screen, the lag goes away.

I have WoW on my left screen in windowed Fullscreen, I'm trying to record it with OBS. I have OBS opened on my right screen. I start the record, since my mouse and the screen currently being used (let's call it the active screen) is my right screen, I see no lag, really good quality no problem on the recording.
Once I move my mouse to the left screen and click on it (to actually play WoW), I can see that my recording preview start to lag immensly. And that's not only the preview, even the actual recorded fle gets laggy when I'm in the game, and goes super fast with no problem when my active screen is not the game.

I never had this problem before Windows 10.

Anyone know what could be the explanation for that?

Note: I never lag in game, the lag is only in the recorded video (and recorded preview).

- - - Updated - - -

My OBS recording show 10 FPS while in game, and 30 FPS (what I have it setup it) while outside of game.

(The actual FPS in game always stay over 60)

[Mythbredor]

What are your system specs and disable max foreground/background fps in advanced settings of WoW. Also set WoW to fullscreen not windowed fullscreen and see if that makes it better.

Also to clarify it's not WoW lagging only your stream? And by "preview" do you mean you're watching your own stream? if so that's normal to lag or seem lower quality while you're streaming, check it on a different device. If you're talking about the preview provided in xsplit/obs that's not supposed to lag but that seems like your system is just too weak to stream at (??? fps and ??? resolution). But as a unpartnered streamer you should be either streaming at 60 fps 720P or 30 fps 1080p and your bitrate should be at 2500 there abouts.