H6837Wi relationship between sun brigtness and VBR(variable bit rate)

Dear Support,
Would like to check with you on the relationship between sun's brightness and VBR(Variable Bit Rate-video setting). I install my H6837WI at my home porch where it is sheltered. During daytime, the area where the camera is viewing is divided to 2 area which are sheltered area and faraway(with sunlight).
As expected,when I use VBR, for area of less details(rotating in area nearer and no sunlight), video shown was smooth(no lagging) BUT when the camera was rotating in area far away  with sunlight, the video shown was lagging(not smooth). The reason most probably was because one area was less details and the other one was more details, so the VBR rate would increase a lot when moving to the more details area and thus more processing power needed. So it lagged.  Of course at night, no problem as black and white & thus much less details, it became very smooth.

Question 1: Is it normal to see the camera lagging(rotating) in area with high details?Setting (VGA 640 X480)

Question 2: I noted that when the sunlight is very bright, the lagging increases badly and it reboot/restart. Is there something wrong with the camera?

Note: I have been testing the camera, and found that if I put the video setting at 320X240 and rotate speed put at high speed. Ex: 1( 0-fastest 10-slowest), the video was very smooth. It seems that if I put rotate speed at 10(slowest), the lagging increases)