SRD75

Once the Memory Usage Monitor plugin is activated, activating or deactivating any other plugin will display the memory used by that plugin. e.g:
Memory usage for WP Memory: 0.02 MB
For accurate memory usage breakdown for each plugin, you must activate or deactivate them individually; you will not see memory usage when bulk activating plugins.

Memory Usage Monitor

Displays memory/RAM usage for each plugin as they are activated and deactivated.

Sergey Biryukov

Converts gettext binary message catalogs to an array of strings. Allows to save some amount of RAM on a shared hosting server. 
Works with plugin and theme textdomains as well as with the default.
Thanks to AlexPTS for the idea.

Pure PHP Localization

Лучший и, скорее всего, единственный рабочий плагин. Спасибо, Сергей

Пожалуй, лучший плагин для кеширования переводов

Converts gettext binary message catalogs to an array of strings.

Memory Usage Monitor vs Pure PHP Localization