There are several issues that can cause lag. For instance, OBS and XSplit gave me completely different experience with the same encoder settings.
XSplit would give me horrible ingame lag, while OBS runs flawlesly.
1. Your bitrate is way too high for the upload speed u have, hence your game has no more bandwidth to work with.
2. Your encoder settings are not properly configured so your PC is having troubles keeping up
3. You are running your game with too high graphic settings, hence putting too much strain on your PC, especially if u have a game thats CPU intensive
From your screenshot, i believe the bitrate is the culprit. Try lowering it to like 1000 and try again