Endless lag sometimes when exiting a nether portal

Were there many mobs around you? I observed this problem when there were a lot of mobs around me, specifically ghasts and large magma cubes.

not regardless of the entities it happens to me, for example it happens to me when I return to the overworld and I have the same number of entities that I have had in previous versions

Thank you for your report!
However, this issue is Incomplete.

Your report does not contain enough information. As such, we're unable to understand or reproduce the problem.

You are welcome to create a new ticket about your issue with more detailed information.
However, please review the Bug Tracker Guidelines and be sure to search for existing issues before writing a new bug report.

Quick Links:
📓 Bug Tracker Guidelines – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki