i inspected easy ui code and found out that when they create dateTimeBox thay create the calendar,spinner and the time box before we pressed the button to show to calendar.
if they will create this on demand only when user click the calendar button the performance is improved to 20ms instead of ~100ms.
i have made this change and it works, if one of the developers will contacts me in private i will send you the modified code for you to observe

tnx in advanced eliraz.