There are times when using the VB namespace may be slower (due to added functionality and / or flexibility, and not because MS wants the VB to be slower).
But in the case of DateAndTime.Now, this is not so. This is just a wrapper around calling DateTime.Now.
, JIT-, ( Release).
: IL DateAndTime.Now:
.method public specialname static valuetype [mscorlib]System.DateTime get_Now() cil managed
{
.maxstack 1
.locals init (
[0] valuetype [mscorlib]System.DateTime time)
L_0000: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
L_0005: ret
}
, :
Return DateTime.Now