Block other processes?

I'm trying to use Squeak to time an external process via a Socket  
Connection.

I've got it working, but I'm suddenly wondering if the variation in  
timing is more due to internal delays in Squeak, than changes on the  
target system.

For example, if the Squeak garbage collector runs while the timing  
loop is running, that could throw off the measurement.

Is there any way to block the execution of other processes while in  
the timing loop?

-- John