Display of mesh with using MeshVS with VBO objects is extremely slow

As experienced during testing OCCT 6.4.0 beta in LH3D-3H software (RINA), when
VBO is enabled, visualization of big mesh (138070 1d elements and 153240 2d
elements) becomes extremely slow (it is just impossible to wait).

The time in this case is spent in graphics driver, with stack traced back to
the cycle found in file OpenGl_PrimitiveArray.cxx on line 641. It seems that
here each 1d element is displayed by separate call to method glDrawArrays().
However, the same occurs when VBO objects are not used, but in the latter case
display is fast. The problem is to be investigated. Possible solution is to
improve logic of choice of using or not VBO found on line 538 of the above said
file, so as to use non-VBO variant in cases when VBO would not be efficient.

As a temporary solution for OCCT 6.4.0, it is proposed to set default mode of
using VBO to False. See proposed correction attached. It is necessary to
correct Release Notes saying that VBO is OFF by default, and describe how VBO
can be enabled (and check this).