==================================== = NOTE: this is no longer relevant for Scratch 3 = ==================================== Using "wait until", with no changes happening anywhere on-screen, can lead to lag. This is because it performs its checks as quickly as it can when nothing is happening on-screen, so we can run into the keyboard/mouse lag issues caused by doing too much work between the 30x per sec screen refreshes. Watch the speed of the counter as you switch the sliders. When all are zero it's very fast - this is also frequency of "wait until" checks.
While all sliders are set to zero, try holding down keys (esp. Chrome), or clicking mouse button anywhere in project window (esp. Firefox - but only on Mac?) Even Safari can sometimes freeze up briefly when clicking red stop icon (notice spinning cursor). Compare with when there are changes happening (switch on glide or rotate), or when using "repeat until" loop containing "wait N secs". [Also, compare behaviour in turbo mode...]
