I tried checking with method profiling and opengl es tracer. Both look ok with and without the object that cause it slow. Just that from opengl es tracer, sometime that object takes 1-2ms just to call the glDrawArray, more than the one with >100 poly with non-transparent texture. Sometimes, it just take ~0.345ms to draw.
However, i did further testing by checking the framerate I print out in onDrawFrame. When I keep scrolling the homescreen non-stop for awhile (I have removed the camera panning for the LWP), the reading shows these:
With that object: ~39-44 fps
Without that object + animated models + few static objects: ~53fps
If I don't scroll the homescreen, it is ~59fps for both cases. Very odd~