Windows Extreme lag despite very low resource usage

[Mihaugoku]

Hello, just switched recently to a new, quite powerful setup and re-downloaded GM:S 1.4 (this time from steam because YYG hates me), and i started a new simple project.
I ran into a very big issue regarding the framerate of my game.
There's pretty much nothing there - just one player object with basic movement.

The FPS, well.. The debugger showed a few thousand, but my in-game counter showed an average of 45FPS, instead of the expected 60.
That i could eventually fix with sleep margin, which got my game back to 60FPS. However, when i opened up a livestream on chrome, my game went back to a crawl, this time at an average of 30~35FPS. I checked my taskmgr, and it showed like 15% cpu usage total, and everything else was almost unused as well, but my game was still barely working.

Does that issue also happen to anyone in old GM versions, and would GM:S 2 help me solve that problem?
What's the issue here? I don't remember this ever happening even on my very old crappy laptop.

=====

Small update - it seems that this issue only occurs when i'm set to windowed mode. When i'm in fullscreen, i'm always at a stable 60fps. Really weird..

 

[The M]

I'm also having this issue in GM:S 1.4. I've had no trouble in the past but took a short break from my project and when I booted it up again today I found the fps to be hovering in the low twenties rather than the 30 (edit: 30, not 60) it should be. I tested another game and it ran at 45 instead of 60. I ran an old .exe and couldn't see any framerate issues there (though that version didn't have a frame counter so I'm not 100% sure). Compiling a .exe kept the slowdown and fullscreen doesn't help in my case I'm afraid. I've not done anything to the Game Maker installation in years so I'm wondering if it could have been a recent windows update that broke something.

It's a little discouraging as my project is both big and soon to be complete and now it's basically unplayable.

 

[The M]

I have found one solution and that is to simply bump up the room speed by 4 which really isn't a stable solution but it works for now. The issue seems to be more like something's wrong with delta time than lag as the game runs fine and the fps is stable, only lower than the room speed. After testing around I found the following pattern applied (give or take one or two fps):

room_speed | fps
30           22
31           25
32           29
33-57        33
58           35
59           42
60           44
61           46
62           49
63           55
64           60
65+          65

I am very confused...

Edit: so apparently there's a field in global game settings where you can specify a sleep time margin. Increasing this to 10-15 ms solves the issue.