Well, does the game work correctly despite that? If you ran the command and then exited to the main menu, this appears for a split second as the framerate stabilizes to the original value.
Viewing post in v9940 - 60fps, chat revamp, mod stuff comments
I run the command at startup through `startup.txt`. Here's its content.
/gml game_set_size(426, 240)
/gml room_speed*=2 current_time_scale/=2
If I set `AlternateSyncMethod=1` at `options.ini` this message is constantly displayed at the title screen and menus. This can be seen in the video.
When setting AlternateSyncMethod to 0, the warning isn't displayed. However, I observe tearing and tiny frame rate stuttering when playing the game, so I have to change the value back to 1.
In general, I think, it's probably better to put warnings in the console or/and in a log file. Or, as an alternative, there can be a command/option to change log verbosity.