Why is my computer lagging? help pls

5500x3d
3060 12gb
16gb 3200

CS2

When I play DM on a CyberShock, the frame rate is normal, 350-450, but there are often moments when the FPS drops and the frame rate increases significantly (for example, it was 4-6, and then suddenly jumps to 13-25).

What could be causing this? Please help me figure it out.