Blender 2.82a is slow in response

I have been using blender 2.82a for last month and it was running smooth 2 days ago. But for some reason, it’s response time is getting really slow in all modes (object, edit and pose). It has been lagging a lot for last two days.But it is still lagging only in one perticaulr file. It only contains a character mesh and an armature. . I am using alienware 17 and only install python 3.7.4, two days ago. I have tried reinsalling the program and also updating graphic card.
Please help!!