It's rare to find a web server with slow disk I/O performance, but Amazon's EC2 micro-instances are one such example. Their EBS disk subsystem access is rated "low", and this can have a detrimental effect on HTTP throughput. [...] This leaves sessions, which can be written to a redundant and fault tolerant storage system. [...] In order to speed up the disk access, a RAM-based disk can be mounted over the session directory. This has the disadvantage of being volatile - the data is lost in case of a server reboot, or the mount point being unmounted. However if tolerable, storing sessions in RAM insulates the application from poor filesystem performance.

He mentions the two types of kernels that can be used, ramfs and tmpfs, and the specifics of using a tmpfs filesystem to implement the technique (complete with command line calls to make it happen).

Most PHP OCI8 users link PHP with the Oracle Instant Client (IC) libraries that handle the underlying "client" (i.e PHP OCI8 extension) communication with the database. IC is relatively small for the features it gives, and is very easy to install. A ZIP or RPM download unpacks a few libraries. [...] Although IC isn't particularly big - and it's getting relatively smaller all the time - there are two ways to reduce its size.

His two recommendations are to use the lite client version instead of the full-blown one (only has common character sets) or you can just remove the JDBC/ODBC/OCCI libraries from the full install. He lists out the files that are actually needed by the OCI8 extension to compile correctly.