I have some concerns I use projeqtor about 1 year ago but recently I noticed a slowness as not possible when connecting and also when changing from one page to another.

Check your server. Maybe he's not poxerfull enought to manage load and/or volumetrics

I would also like to know if it is possible to create a central directory accessible to users from the tool, if so how to do it?

No, Projeqtor stores data in a database, not in folders

And finally, is it possible that the available contact directory contains the complete visibility of the stakeholders? And how to make the recovery of the existing data.

Yes, you can add as many contact as you wish, and can import contacts from CSV / XLSX files