i am using the classic definition of lagging indicator.
tick is not a lagging indicator by that definition - which is an indicator that gives a current value, based on past data
an RSI, a MACD, etc. are lagging because they apply a formula to a series of datapoints (which are necessarily mostly in the past), to give a value. similarly, a moving average is lagging.
tick is not a lagging indicator. yes, there is lag between the time it happens and when it shows up on your screen, but that's true even with price. and price is the ultimate NONlagging indicator
tick is a very useful indicator because it is not some derivative formula based on the past, but an exact indication of the buying pressure in the relevant market (NYSE TICK etc.).
it is what it is.
i have a # of setups that take tick readings into account. i think if you trade frequently enough you will begin to see how tick can be used to help frame trade setups.