Lag with three.js

Questions
1

My three.js used to work pretty smooth on my laptop. But recently, from some days ago, whenever I add something to my scene, it hangs my browser.

2

Does that also happen when running official three.js examples?

3

let me try

4

nope no lag, three js examples run smooth like butter.

5

If I run three js in any online code platform, there is no lag. It lags only on my PC.