php.net: Description of core php.ini directives / File Uploads
www.radinks.com: PHP Upload Configuration
Bár egyikben sincs utalás, hogy timeout lenne a hatása, ha túlléped őket, kivéve itt:
max_execution_time integer
This sets the maximum time in seconds a script is allowed to run before
it is terminated by the parser. This helps prevent poorly written scripts
from tying up the server. The default setting is 30.
The maximum execution time is not affected by system calls, stream
operations etc. Please see the set_time_limit() function for more details.
You can not change this setting with ini_set() when running in safe mode.
The only workaround is to turn off safe mode or by changing the time limit in the php.ini.
Your webserver can have other timeouts. E.g. Apache has Timeout directive,
IIS has CGI timeout function, both default to 300 seconds. See the webserver documentation
for meaning of it.