In Illustrator, it looks like the OS is coalescing events when you get ahead of the program.
In Photoshop, it records your mouse/tablet movements and plays them back correctly even if you get ahead of the software.
As for why you are getting ahead - you are doing fast gestures, but the apps should be able to keep up unless you're working on a very high resolution document.
We have seen bugs in third party plugins, bugs in video card drivers, and sometimes wacom drivers cause delays while painting.
I tried old drivers and also the newest drivers but it is always the same problem. I also uninstalled the wacom driver but the problem is still there when painting with the mouse. I don´t use any third party plugins.
What zoom level are you brushing at and what kind of brush are you using. I find a lot of lag when the document has a large number of pixels and you zoom out like fit on screen. Additional lag introduced when wet mixer brush are used a large tip size increase the lag even more.
Remember Photoshop was designed to be an image editor. Paint is a nice addition but not Photoshop main gold. If you want to paint I'm sure a program designed to be a paint program would perform better and have more painters features. A paint pint program may paint on the scaled down image and apply the paint to the large document in the background where is look like Photoshop Paint on the large document layer then scale the results down to the zoom out view for there is no lag in Photoshop when you paint at the 100% or higher view.
NOTE: When perusing the community, the topic ‘LAG’ comes up too much. I have been experiencing lag issues since the update to CC2014.2.0. As with everyone else, the workstation is built for design/graphics so the finger only points to the updater. Perhaps it is in the Flash itself, as that seems to be the source of the lag. The program starts but takes longer than the previous version to become active/useable (I see the toolbar but have to wait for it to work). The Flash preloader should never show but does often enough to be annoying.
If those of us who have systems capable of running 3D rendering are only having lag issues with PS, then the issue is the PS program itself. As for me, the updater shall be uninstalled and a more stable CC version reinstated; at least until a patch is offered.
(Maybe a patch will be here on Monday…)
The only way Flash would be involved is if you have Flash based panels/extensions open.
Most people are not seeing lag in CC 2014 -- but most of the reports of lag have been due to causes outside of Photoshop (firewalls, Kaspersky antivirus (update), video drivers, etc.).