Script for automatic spell check

There is a database with nearly half a hundred terms in UTF-8 encoding. All terms have been moderated by moderators and are 100% accurate.
It is possible on the site to enter terms by users manually in certain fields.
It is necessary to make sure that either automatically when saving or automatically at a given interval, the script checks the data entered by users and automatically corrects them for correct ones, or in case the level of similarity is too low with all terms in the database, then sends it to the moderator for verification (it is entered in a certain database table).
The script should work quickly and not hang the work of the site and server.