Bug 354656

Plasma tooltips that are shown when the mouse hovers over a panel elements such as icons and system tray are slow and consume too much CPU. I can see that the frame rate at which these tooltips are updated is lower than the rest of the desktop compositing.

I can occasionally observe that the tooltip appear with a noticeable delay (up to several seconds), even after I moved the mouse away from the element, and in those cases the tooltip does not disappear until I move the mouse back to the element. This is very annoying.

In contrast to that, the tooltips that appear in applications (e.g. in KDE System Settings) are much swifter. Other animations, such as moving windows around, is also quite responsive.


Reproducible: Always

Steps to Reproduce:
1. Create a panel with 15-20 application launching icons on it. You can also have a system tray on it as well.
2. Try to move the mouse over the icons. Keep moving as the tooltips with application names start to appear.
3. Observe the CPU load and interface sluggishness.

The hanging tooltips typically appear in the every day work, when you quickly move the mouse to an icon to start the application and then move the mouse away. The tooltip appears with a delay and keeps hanging.

The problem appears even if no applications are running and CPU is pretty much idle, so this is not a resource shortage issue.


Expected Results:  
The performance should be much better, the interface should be as swift as the normal tooltips in applications. I would accept an option to replace all Plasma tooltips with normal tooltips.

Kubuntu 15.10, x86_64, Nvidia drivers 355.11. Core i7 2600K, GTX980, 16 GiB RAM, no swap.