I need a help with the following problem.

You have described a task but not where you think there is a problem. Perhaps the problem is with your algorithm - but since you have not described your algorithm nobody can say. Perhaps the problem is with your code - but since you have not shown your code nobody can say. Perhaps the problem is with your test suite - but since you have not shown your tests nobody can say. Perhaps the problem is with your operating system or your environment or your hardware limitations or ...

As you are not new here, leoberbert, you must have seen how good questions elicit good answers. Ask a good question, brother. Wisdom may flow.