Tested a bit on my server, as promissed. Didn't found noticeable difference: server load (average) unchanged, page generation time (average) unchanged.
May be, I do somerthing wrong
Probably, effect can be gained in 2 cases:
- on apache+modphp, with bunch of active processes.
- if additionad mods are written dirty.
Config: (php 5.2.6/eaccelerator/nginx) + (vb3.7.4/vbseo/memcached) + (Core Quad 6600 / 4Gb Ram)
Top = 1.5 (100% = 4)
~200 000 php page hits dayly.