Bump default check interval to 100 instructions. Computers are much faster

than when this interval was first established.  Checking too frequently just
adds needless overhead because most of the time there is nothing to do and
no other threads ready to run.

Python/ceval.c

@@ -469,8 +469,8 @@ static int unpack_iterable(PyObject *, int, PyObject **);
 
 /* for manipulating the thread switch and periodic "stuff" - used to be
    per thread, now just a pair o' globals */
-int _Py_CheckInterval = 10;
-volatile int _Py_Ticker = 10;
+int _Py_CheckInterval = 100;
+volatile int _Py_Ticker = 100;
 
 PyObject *
 PyEval_EvalCode(PyCodeObject *co, PyObject *globals, PyObject *locals)