The refresh rate of your monitor and the type of monitor you use can affect how the game is played, mainly the response time between your inputs and what appears on your screen. Generally the higher the refresh rate (hertz) your monitor is, the faster the response time/input delay is. The type of panel you have for your monitor can also affect your response time. OLED and QD-OLED monitors have the best response times, generally being around 0.03ms, which is faster than LCD or even TN panels. However, OLED and QD-OLED monitors are pretty expensive, with some of the cheapest ones still being around $500 in the US, so it's better to just have a higher refresh rate first, then worry about getting an OLED or QD-OLED.
I'd recommend getting a monitor that's at LEAST 144hz, an even better idea would be to get a monitor that has a refresh rate that's divisible by 60 (stuff like 180hz, 240hz, 300hz, 360hz, etc.) so that SMB1 doesn't stutter or jitter slightly (since the game runs at about 60 fps).
I should clarify that the actual game or emulator itself isn't affected, just the input delay between your controller/keyboard and the response on your screen.
Effective immediately, any submissions using the SNES9x emulator will not be verified. The SMB1 mod team has concerns about its integrity due to its ability to overclock and remove lag frames, which may not be easily detectable. Additionally, we request that all BizHawk submissions avoid using the S