I just opened Blender to make a quick triangle model for my game, but all of a sudden everything’s extremely laggy and slow. I don’t remember doing anything differently this time or changing anything since the last time I used it, any suggestions on how to fix it?
Using Win 10 and a notebook with nVidia graphics card, I assume? Then please use the forum search, for crying out loud!
This has been asked a gazillion times before…
Sorry, I’ll look it up 
Hint: The automatic update of Win 10 installs old/faulty graphics drivers. Install the newest ones from nVidia or set Blender to use the onboard graphics.
BTW, you might have found those other threads, if you hadn’t also posted yours in the wrong section of the forum…
“Blender Artists Website Support” is for issues you have with this very website, not for issues with Blender.
The first page alone in the “Technical Support” section shows four current threads on the same topic…
Moved from “Blender Artists Website Support” to “Technical Support”