Why does the server give css, js files for a long time?

Question

caching

Hello. The problem is that when loading the site, css, js files are loaded for a very long time. All files are compressed and weigh 50-200 KB.
Sometimes files weighing 100 KB are loaded in more than 3 seconds
Website on a VPS with KVM virtualization.
The interesting thing is that if you connect libraries (jQuey, Bootstrap) via cdn, then it loads ten times faster.

Answer 1

because you set up the server badly and did not set up the user side static caching