In the default settings of the game, the tick is set to 20 per second. Changing random tick speed actually does not change the speed of ticks, but changes the number of blocks per chunk that are randomly selected for block random ticks.
For an example, random ticks on grass blocks spread the grass nearby dirt blocks, if more grass blocks are selected per tick, grass will spread in fewer ticks than otherwise.
How to Change Tick Speed in Minecraft
To change tick speed in Minecraft you need to enable cheat. Once the cheats are enabled you have to use this Minecraft tick speed command:
In the example above, the random Tick Speed has been changed to 60. You can put any number from 0 to 255. But remember 0 will disable random ticks all together
This trick is useful if you want your plants to grow fast, but as a consequence some, plants might decay faster if the number is set too high. So please be aware