Quickly move the mouse over a link so it just briefly touches the link, leave the link and quickly move back on the link: No popup will be shown, even if you longer dwell for longer. The movement needs to happen in between the `ABANDON_END_DELAY` 300 ms to show that effect. While for #page-previews the delay works well, the much smaller #reference_previews (that often appear right after each other) need a shorter time span. Especially, since reference targets are much smaller than page preview targets, it might make sense to counterbalance this.
See also comment in T214693#4924357
 The delay for reference previews is reduced to 150 ms.
 The delay for page previews stays at its current rate
- The delay is about waiting until the popup is being shown. Thus it does not matter whether you have been before.
- This ticket is independent from the bug that sometimes no popup appears if you hover too quickly between preview types
- The code is built in a way that we are never seeing empty popups, in the worst case the popup just takes a bit longer too appear