What does it do
The waterfall particles are being displayed every 0.5 seconds on a 20 blocks radius around every players!
Is it advised on servers?
If your server has a good processor and doesn't use too many datapacks it should be ok! It could only causes client lag if several players are in the same area near a waterfall (waterfall at spawn for example) because each players would display particles to each others repeatidly in a similar area causing a massive amount of particles.
Can I use it on a singleplayer world?
It shouldn't be an issue if you have a not too old processor. When used in singleplayer, you may have a performance impact depending on how recent your computer is, because the main function has 18000 commands, but the lag comes from the task of running commands, not from the particles. The timer prevents lag from particles in singleplayer. FPS aren't impacted, only processor usage.
Possible console error
If you get error in the console regarding max commands allowed per tick, run /gamerule max_command_sequence_length 100000 or more (default to 65536). You will only get this error if you use other datapacks.
