I've split out the ipSecurity section of my web.config file to it's own file. I use this files to block users from countries other than Canada/USA.
This file is 2.6 MB in size as it contains IP deny entries for the whole world.
I had to override the maximum size allowance for config files because it's so big.
I've noticed that restarting the web service or web site takes a lot longer with the large config file. With a 2.6 MB files it takes about 5-10 seconds to reboot the site / app pool / service.
I experimented with even larger files up to 30 MB and this causes the restart to take 60-120 seconds.
I have a feeling it's also causing issues with app pool recycling but I'm not sure.
Are there any other side effects to having a large config file?