retest / consider removing the implementation of
ZK-1885 for modern browsers
consider the simple example:
manually counting the "forced reflow" warnings in chrome developer tools resulted in ~150 warnings
more complex examples easily result in 1000s of reflows = bad performance
Where possible first collect read styles of multiple/all affected widgets, then update styles (only if needed!) in a separate loop.
Avoid alternating between read/update/read/update styles
Most prominent example in zk.Widget.resetSize
Here n.scrollTop/n.ScrollLeft trigger a css reflow followed by an immediate style update.
The next call to resetSize will reflow/update again
A nice collection of what might cause a reflow is summarized here: What forces layout / reflow