Eaccelerator is a PHP accelerator/encoder/caching utility that is based
off of the old mmcache (which is no longer being maintained).What Eaccelerator does is: it caches your PHP scripts so that the database is no longer being queried every time someone needs a script. This is
particularly useful for large forums, but pretty much anyone can benefit
from it. Since these scripts are cached, youll notice a decrease in
memory use and server load.
Now, onto installing this!
============================
Installing Eaccelerator
============================
1. First, youll want to SSH into your server as the root user. you should
be in the default directory now. If youre not, type in cd ~
Now well make the eaccelerator directory:
mkdir /ea/
cd /ea/
2. Now well grab the files, and untar them:
Notice that its a tar.bz2 file, so we need to decompress it twice.

wget http://oratoronline.com/how2/Eaccelerator/eaccelerator-0.9.5.2.tar.bz2

bzip2 -d eaccelerator-0.9.4-rc1.tar.bz2

tar -xvf eaccelerator-0.9.4-rc1.tar

3. Now that we have done that, lets install Eaccelerator:

Note: in the following export command, you need to point that to where
PHP is installed. For most, its usually either /usr/ or /usr/local, but
it may be something else.

cd eaccelerator-0.9.4-rc1/

export PHP_PREFIX=/usr

$PHP_PREFIX/bin/phpize

./configure –enable-eaccelerator=shared –with-php-config=$PHP_PREFIX/bin/php-config
make
make install

4. Its basically installed, now we need to edit the php.ini files to
include Eaccelerator. This is usually found in the /etc/ folder, but if
you cant find it, run a “locate php.ini (without quotes) to find it.
You can use pico or vi, its your choice:
cd ~
nano /etc/php.ini
=======================================
For a PHP extension install (most will probably want this)
=======================================
extension=eaccelerator.so
eaccelerator.shm_size=16
eaccelerator.cache_dir=/tmp/eaccelerator
eaccelerator.enable=1
eaccelerator.optimizer=1
eaccelerator.check_mtime=1
eaccelerator.debug=0
eaccelerator.filter=
eaccelerator.shm_max=0
eaccelerator.shm_ttl=0
eaccelerator.shm_prune_period=0
eaccelerator.shm_only=0
eaccelerator.compress=1
eaccelerator.compress_level=9
==========================================================================
For a Zend Extension install (only if you have Zend Optimizer installed, or
if youre going to install it
===========================================================================
zend_extension=/usr/lib/php4/eaccelerator.so
eaccelerator.shm_size=16
eaccelerator.cache_dir=/tmp/eaccelerator
eaccelerator.enable=1
eaccelerator.optimizer=1
eaccelerator.check_mtime=1
eaccelerator.debug=0
eaccelerator.filter=
eaccelerator.shm_max=0
eaccelerator.shm_ttl=0
eaccelerator.shm_prune_period=0
eaccelerator.shm_only=0
eaccelerator.compress=1
eaccelerator.compress_level=9
cd ~
mkdir /tmp/eaccelerator/
chmod 0777 /tmp/eaccelerator/
5.After installed restart apache to check eaccelerator is installed.
service httpd restart

Verify:
=========
Run following command, and it should show Eaccelerator in the output as.

php -v
PHP 4.4.4 (cgi) (built: Feb 7 2007 08:27:53)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v1.3.0, Copyright (c) 1998-2004 Zend Technologies
with eAccelerator v0.9.4-rc1, Copyright (c) 2004-2004 eAccelerator, by eAccelerator
with Zend Extension Manager v1.2.0, Copyright (c) 2003-2006, by Zend Technologies
with Zend Optimizer v3.2.2, Copyright (c) 1998-2006, by Zend Technologies