Hello - I am finding that printing to the console from a function that is invoked from tcl/tk (i.e. pushing a button) is really slow. Consider the following example. doStuff <- function() { source(file.path(system.file(package = "base"), "demo", "is.things.R"), echo=TRUE) } tt <- tktoplevel() button.widget <- tkbutton(tt,text="Do Stuff", command=doStuff) tkpack(button.widget) I find that this is significantly slower than if I ran source(...) directly from the console prompt. In the back of my mind, I am thinking this might be some effect related to multi-threading and the locking/unlocking of a mutex - am I right? Any help to speed this up would be appreciated. Thanks, Alex Couture-Beil PS: I am running this test with R 2.4.1 on WinXP