I've had mixed results.
We give a seperate drive dedicated to page files on all our virtual machines and leave the settings as system managed. However on some very memory intensive app servers I've found performance is increased by setting specific page file settings. For example on the GPS business intelligence servers (2008 R2) which have 8gb memory, system managed page file never appeared to go beyond 6gb and performance on these boxes was poor. I set custom sizes of 10-15gb and the performance is much better.
We give a seperate drive dedicated to page files on all our virtual machines and leave the settings as system managed. However on some very memory intensive app servers I've found performance is increased by setting specific page file settings. For example on the GPS business intelligence servers (2008 R2) which have 8gb memory, system managed page file never appeared to go beyond 6gb and performance on these boxes was poor. I set custom sizes of 10-15gb and the performance is much better.