Why is Roblox lagging in the recording?

I started recording YT videos yesterday. Minecraft works really well but I also want to record Roblox. I record with OBS and my Roblox runs absolutely smoothly the whole time, but the recording is jerky all the time. What's going on? How can I change this?

Have a look in the settings of your recording app, maybe the FPS number is low? Otherwise, if the game runs smoothly but the recording is not then it must be due to the recording app. For me everything runs smoothly at 60FPs.

How much FPS does it get smoother at? If I increase or decrease it?

FPS means frame per second and the more you set, the smoother the recording, but note that 60FPS is more than enough, and of course it also draws more power.

Do you know about OBS?

No, because I have a Samsung cell phone and the S9 has an integrated recording app

I increased the FPS and I think it's even more lagging in the recording…

In any case, you have to adjust it so that the performance also fits. As I said, I'm not familiar with OBS but maybe 30FPs are enough? Fiddle around and find out more on the Internet.

Check the OBS settings. If you have a good PC, take the settings from a bigger YouTuber (recommend Nilson)