When To Split A Page

I know that a work's examples of tropes like Tear Jerker and Ho Yay are made into their own pages when they're too big to be on the YMMV page, but how big is so so big that it requires a page split? What is the criteria for when a page should be split?

A subpage containing examples of a particular trope (or work examples for a particular media category) may be created with as few as three examples, although it's usually not done until quite a bit more have accumulated.

Any wiki article must be hard split when it nears 500,000 characters in size, as the wiki parser will crash shortly thereafter. Most articles are split well before reaching that size.

So, as a rule of thumb, when is a good time to start splitting articles? How big can an article get before we decide to start breaking it up?

The 1.3 redesign gives articles a lot more room before they break for size, but a rule of thumb is when it starts taking too long to load in your browser.