Since it was agreed to keep performance schema intact, further analysis will be done with performance schema compiled out.

I suspect that the various inline_mysql_ functions in include/mysql/psi/mysql_thread.h can lead to serious code bloat when the performance schema is compiled in. I partially worked around those in MDEV-21452 for the popular lock_sys.mutex and dict_sys.mutex by defining an explicitly non-inlined entry point like this:

#ifdef HAVE_PSI_MUTEX_INTERFACE

  /** Try to acquire lock_sys.mutex */

  ATTRIBUTE_NOINLINE int mutex_trylock();

  /** Acquire lock_sys.mutex */

  ATTRIBUTE_NOINLINE void mutex_lock();

  /** Release lock_sys.mutex */

  ATTRIBUTE_NOINLINE void mutex_unlock();

#else

  /** Try to acquire lock_sys.mutex */

  int mutex_trylock() { return mysql_mutex_trylock(&mutex); }

  /** Aqcuire lock_sys.mutex */

  void mutex_lock() { mysql_mutex_lock(&mutex); }

  /** Release lock_sys.mutex */

  void mutex_unlock() { mysql_mutex_unlock(&mutex); }

#endif

Duplicating complex inline functions not only makes the executable bigger (and thus makes instruction cache misses more likely) as was the case in MDEV-22721. In this case the duplication could also make branch prediction harder.