I would guess that the reason could be the call to wglSwapIntervalEXT on line 295 of crtemu.h. Try removing that line and see if it works any better. If not, I can take a deeper look at some point
This line here: https://github.com/mattiasgustavsson/dosbox-crt/blob/880995bdb630518cea12c70ea56...
holy shit that actually worked, ill be honest, i didnt expect a response, thats why im only checking now 4 days later
im gonna tweak it a lil bit more before uploading this, maybe then you can check it out, see how much i butchered your code trying to get this dumb idea of mine to work
on the bright side, you can use custom frames now, figuring out how to generate a hex array in the same format as the one in crt_frame.h sure was an interesting detour in my quest to reverse engineer your code
ok is almost ready to publish, still some bugs left but it'll do for a version 1.0, i just wanted to ask you if its ok if i repackage your DOSBOX-CRT folder with the demos, custom menu, etc, and simply replace your .exe with mine, and add some config files for the frame
heres the repo if you want to give it a look
https://github.com/NukeKangaroo/dosbox-crt-widescreen
oh and another preview image
https://steamcommunity.com/sharedfiles/filedetails/?id=3482516312
i added options to toggle the CRT filter, to play only with the custom frame, and an option to have the viewport fill up the screen vertically, its all set in a separate crtemu.conf file