Why does the Drupal admin panel slow down?

Question

Drupal

Good afternoon, at one point, the drupal 6 admin panel began to slow down terribly, and the server responds quickly, and then it processes js for a long time. But the strangest situation occurs when processing ajax requests, the scripts are loaded quickly, but between them there are some strange pauses of several seconds. Could you give me an idea of ​​what could be wrong? Thank you.