"include" needs up to 6 seconds to load a 15kb-script. The included script (text.inc) only contains some variable-declarations, for example:
$x = "a 1kb long text ....... ";
$y = "a 2kb long text .......";

1) This Problem seems to occur only with PHP4 on Windows (PHP3 on LINUX is OK, also PHP3 on NT)
2) When I include the declarations directly in the caller-script, execution-time reduces to 0.01 seconds (600 times faster!)
3) When I comment each line in "text.inc", the execution-time remains the same - so the reason seems to be the size of the file itself and not the evaluation of it
4) When I load the file text.inc into a $variable and then evaluate the $variable, also 6 seconds are needed. I detected that loading of the file is quite fast and nearly all the time is consumed by the "eval"-command (this is contrary to point 3)
5) When I decrease the size of the included file, the execution-time decreases proportionally
6) using "include" or "require" makes no difference

"include" seems to be buggy in another way: sometimes (1%) re-declaration-errors occur - obviously scripts (or included files) are evaluated two times. The error is not reproducable.