Hi Deven,
after reading https://github.com/phpmyadmin/phpmyadmin/issues/11597 and looking at PMA_checkRequiredPrivilgesForAdjust() I am convinced that this function needs caching.
Can you have a look at PMA_analyseShowGrant() and see how we use these functions:
PMA_Util::cacheExists() PMA_Util::cacheGet() PMA_Util::cacheSet()