Saving Failed Ajax called failed

Hi, I have 2 issues

1. I have almost 2500 records in the table. When I open the list page it’s talking almost 10 mins to open.
2. After adding the row or any updating the row, I am getting the error Saving Failed: Ajax called failed: error – internal server error. Try again holding down the shift key.

Records are updating but i am also getting the above error. Can you please check it once what is the issue?

here is the image link https://ibb.co/1s3qFyw