Dear list, I have this minimal sample: \setupinteraction[state=start] \setupinteractionscreen[option=max] \startJSpreamble {varia} used now var transitions = [1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000]; var msecs = 0; function step_clock() { try { ++msecs ; if ((msecs >= (transitions[this.pageNum]/10)) && ( this.pageNum < this.numPages )) { ++this.pageNum; }; } catch (e) {} } advance = app.setInterval ("step_clock()", 1); advance.count = 0; \stopJSpreamble \starttext \dorecurse{10}{\startTEXpage[pagestate=start, offset=1em] \pagenumber \stopTEXpage} \stoptext Acrobat is required. And I have an issue with it Each slide takes a full second (1000 milliseconds). But the conditional in step_clock() needs to divide the elements from transitions array by ten. Otherwise it is ten times slower. Am I missing something here? Or why is "step_clock()" ten times slower than it should be? Many thanks for your help, Pablo -- http://www.ousia.tk