Add notes about database performance for MySQL
Add notes about database performance for MySQL

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jirutka/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,iiet/iiet-git,t-zuehlsdorff/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,axilleas/gitlabhq,iiet/iiet-git,t-zuehlsdorff/gitlabhq,dreampet/gitlab,axilleas/gitlabhq,axilleas/gitlabhq,dreampet/gitlab,dreampet/gitlab,iiet/iiet-git,mmkassem/gitlabhq,jirutka/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,stoplightio/gitlabhq,t-zuehlsdorff/gitlabhq,mmkassem/gitlabhq,t-zuehlsdorff/gitlabhq,jirutka/gitlabhq