Steps to Reproduce

1. load the attached zul
2. click the groupbox with "performance problem"

Current Result

it takes about 3 sec

Expected Result

less than 1 sec

Debug Information

• the groupbox contains a big HTML table

Root Cause

The slow rendering is caused by open animation, slideDown and slideUp, which are based on jQuery animate.

Workaround

zk-4090.js - only works for org.zkoss.zul.client.rod="false"