Hello Rohit_hp,
Does the issue only happen when scrolling using the two finger scrolling gesture? Do you experience issues with any other gestures? What process did you use to adjust the scrolling speed? That information will help us get a better understanding of the issue.
Please be sure to check out this link, which has some information about gestures, and will guide you through how to manage the Trackpad settings, and may help: MacBook Air trackpad
Customize your gestures. In System Settings, click Trackpad in the sidebar. You can do the following:
• Learn more about each gesture
• Set the click pressure you prefer to use
• Decide whether to use pressure-sensing features
• Control the tracking speed
• Customize other trackpad features
Note: If you would like to use a Bluetooth® mouse or trackpad in addition to the trackpad on your MacBook Air, learn how to set it up at Work with wireless accessories.
You can also find some additional information about scrolling speed here, that may be helpful as well: Change mouse tracking, double-click, and scrolling speed on Mac
Change double-click and scroll speed
1. On your Mac, choose Apple menu > System Settings, then click Accessibility in the sidebar. (You may need to scroll down.)
2. Click Pointer Control on the right, then do any of the following:
• Adjust how fast you must click for your Mac to recognize a double-click: Drag the slider next to “Double-click speed.”
• Adjust how quickly the pointer moves when you scroll: Click Mouse Options, then drag the slider next to “Scroll speed.”
Thanks!