I need to now where the cached files are stored, to install the phpexpress on a shared web hosting system and dont´t suffer security risks.

Thanks.

It does not store any files. All chaching is done in memory. So I believe there is no security risk. If we were to implement caching on disk (and we may consider it), we would add this into phpexpress configuration directives.

BTW, how did you solve the problem that the users can access other user files in the shared hosting environment?