Description:
------------
When calling apc_store, if it needs memory, it might take a long time to free if several user variables are stored.

I think the problem comes with a modification at line 659 / 660 of php_apc.c that now has this code:

 apc_cache_expunge(apc_cache,t);
 apc_cache_expunge(apc_user_cache,t);

If several variables are stored in the cache then it takes a long time to free some.

Reproduce code:
---------------
<?
  set_time_limit(0);
  for ($i = 0; $i < 500000; $i++) {
    $u = apc_cache_info("user", true); $u = $u['mem_size'];
    if ($i % 50000 == 0) echo "--- $i $u\n";
    $x = microtime(true); apc_store($i, $i); $x = microtime(true) - $x;
    if ($x > 3) die("$x seconds taken for $i\n");
  }
  echo "test";
?>


Expected result:
----------------
An echo every time $i % 50000 == 0
test


Actual result:
--------------
--- 0 0
--- 50000 5177780
--- 100000 10377780
--- 150000 15677780
76.2400200367 seconds taken for 163626

(it takes a long time at iteration 163626 when cache is full)