DO NOT USE THIS OPTION IF YOU DON'T UNDERSTAND WHAT IT DOES
DO NOT REPORT ERRORS OR BUGS IF YOU DID NOT TEST WITHOUT THIS OPTION SET
THIS OPTION MOST LIKELY WILL NOT BOOST YOUR PERFORMANCE, ITS MOST LIKELY YOUR BACKEND THATS SLOW
number of worker processes to spawn. This is usually only needed on servers which are fairly loaded and the network handler calls delay often (e.g. new requests are not handled instantaneously).
If you use server.max-worker, the mod_status module will not show the statistics of all the server's children combined. You will see different stats with each request. mod_status documentation
Other modules are affected by this, too; every worker works for his own and there is no communication between them. Your log files may get screwed.