LithuaniaThis is not a new thread but I hope I can still be helpful.
The problem here is that the NES is designed to run ~60.09 FPS and emulators accurately replicate that framerate. Your monitor is probably set to 60 hz so it's 60 FPS and it doesn't match by a tiny amount. So if you play with Vsync there is going to be input lag / stuttering. Without Vsync you're going to have some tearing.
What fixes this problem for me is having a monitor with AMD Freesync (or adaptive sync in general). Yup, the tech that is made for modern gaming GPU's and monitor's actually helps a lot with NES emulation. It automatically sets monitor's refresh rate to that ~60.09 so there's no tearing and no lag/stuttering. Perfectly smooth gameplay in my experience.
I don't know what hardware you have but it's likely you have a basic monitor or laptop that doesn't support adaptive sync of any kind. You could consider getting a monitor that's at least 75 hz and has Gsync / Freesync tech. Your graphics card must also support adaptive sync but pretty much all modern GPUs do, even Intel integrated ones. You can google "adaptive sync" for more information about this.
As an alternative you can try using the MesenRTA emulator. It's allowed by SMB1 community and it's a very good emulator, it might work better for you. Also it has a "integer FPS" option that makes games run at flat 60 FPS. However, that means your times are going to be very slightly slower because the game will be slowed down by a tiny amount. That tiny amount can accumulate to a few seconds depending on a run.
One other thing that you might look into is custom resolutions and monitor overclocking. Pretty much all monitors can run 1hz or more above their spec. You could create a custom resolution with software like Custom Resolution Utility (CRU) and create a resolution with 60.09 Hz to match NES framerate. I experimented with this in the past when I saw this idea on the internet but I was not successful, I guess my monitor just doesn't like such shenanigans or I was doing something wrong. Your mileage may vary with this.
