When apache reloads cofig files all instances of passenger are stopped and must be spawned again, it creates a problem, because spawn of rails application isn't fast process. Is there any workaround to prevent this behavior?
Limit the number of changes in your apache config? Plan and think ahead!
It depends on why you need to reload apache. Many settings have a generous context and can be set in .htaccess files, changes there don't require a server reload to take effect. Those .htaccess files can be a nuisance to maintain and will result in a minor performance penalty as well though.
mod_vhost_alias can be a solution when you often restart to activate new virtual hosts.