In an optimization strategy, to be able to obtain an ideal optimization of MySQL, it is essential to have an understanding of the operation in the backend, to be able to make the right adjustments.
It's like when you bring your vehicle to the garage to check an abnormal sound. A competent mechanic will be able to give you good recommendations and do the right thing to correct the situation because he knows how the engine works, and it is the same with MySQL and optimization.
MySQL, like any other database, needs somewhere to store its schema names, table definitions, and other metadata; these are most commonly stored in a combination of different locations, including .FRL, .PAR, .OPT, .TRN, and .TRG files. This has gradually become a bottleneck in various contexts over time.
A visual example of files external to MySQL tables can be seen in the following...