When digging stone-like blocks, Tungsten requires 38 ticks. Thus, it is more efficient to use a Lead (36) or Silver Pickaxe (33), as they will dig faster, despite needing one more hit. However, Tungsten is marginally better than an Iron Pickaxe, which would be 39 ticks.
When digging dirt-like blocks, it is faster to use the Tungsten Pickaxe because it only needs one hit (19 ticks) instead of two.
↑A tick is a time unit countable by the software. Most of Terraria's updating logic happens every tick. A tick has the length of 1/60th of a second, hence there are 60 ticks in a second and 3600 ticks in a minute.