Dear Nouman,
The issue you’re describing seems likely related to ventilation or cooling. Since you’ve mentioned that the fan is working, the probable culprit could be the thermal paste. If you’re familiar with hardware installations and feel confident, you might be able to replace the thermal paste yourself. There are many guides and videos available that can help you with this task.
Another thing to consider is the accumulation of dust and debris in your system, as this can also slow down your computer.
Lastly, it’s worth mentioning some best practices to avoid this issue in the future: try to use only one memory-intensive application, such as Premiere Pro or After Effects, at a time. Additionally, avoid using Google Chrome while editing video, and if you must use it, keep the number of tabs to a minimum.
Best regards,
Ivan