this is not cheat value
shutter speed 1/5000s is possible coz the shutter is using electronic window gate
while lx5 using is using mechanical window gate... tat y it have longer 1/250s shutter time

to understand why your ceiling's fan bend...
i believe it is due to the sensor itself
it simply didnt capture light fast enuf

u can simply test this theory if u use some heavy lighting on the ceiling fan b4 u capture the image 
do tell us ur result 

so electric shutter even 1/5000s, still lose to mechanical 1/1000s???

Guys, I get quite low in Antutu Benchmark(lower than original) when I am using Latest Dev ROM...
Is there's something I can do to fix this? Or I should just ignore this?

Thanks!

I am not a photographer too, but it seem hdr can capture "More Light" lol "

welll.. just RM800 phone, i don't demand on it

HDR is good when there's too much of one thing like too much light at one area.
So by taking 3 pictures with different levels of contrast, the software can interlace & take the best parts of each picture.
But don't compare with DSLR la, example a D7000 can set at 5 pictures, more levels to play around 

Use A Better Camera instead of stock camera for HDR, ABC takes 3 pictures while stock takes only 1 but use software to manipulate to be HDR-ish

shaky hands maybe because you're holding it wrongly? 
I always tuck in my elbows to my body while holding the phone when taking pictures especially when don't have any tripods laying around