The output_buffering directive and Bitrix?

Question

1C-Bitrix

Good day to all! Recently, the site had problems with the session. When you try to change the properties of Bitrix, do not let it in and require authorization:

And it also gives an error:

php could not start session because headers have already been sent

In short, I came up with the simplest solution - to change the value of the output_buffering directive, from the standard 4096 to On (in my opinion, then the buffer size increases to 16Kb). The error is gone. But I have a question, how can such a decision affect the site?!?? Could this degrade its performance?!??
Thank you all in advance)