Mounts2SD is an Android application which goal is to increase space for user, system and applications. This is very interesting for old devices which have low space on the internal memory and SD card slot. It is developped by dk_zero-cool, a XDA contributor (applications, ROMs).
The idea behind the Mounts2SD script is to use init.d to make new mount points for /data/app, /system/app, /data/dalvik-cache, /sd-ext and others on the internal memory or SD card. The application lets the user choose where to put his apps, data and cache.
In theory, SD card should be slower than internal memory but with a good SD card, fstab which allow to set readahead parameter value and Mounts2SD app which could disable unused features like EXT journal, no slow down will be noticed.
As thank you for his hard work, I translated the dk_zero-cool application in my mother tongue language. More information about Mounts2SD below: