I read on planetlotus.org about Bob Balaban's test of the speed difference between s="" vs len(s)=0 checking ( http://www-10.lotus.com/ldd/bpmpblog.nsf/dx/performance-testing-technique ).

My test agent looks like this:

Sub Initialize    Dim n As Long, ni As Long    n=10 ' number of test repeats    Dim t1 As Double, t2 As Double, tn As Double, tt As Double    Dim i As Integer, j As Integer, k As Long    Const x=10000    Const s="xxxxxxxxxx"    For ni=1 To n       t1=Timer       For i=1 To x          For j=1 To x             k=Len(s)=0          Next       Next       t2=Timer       tn=t2-t1       tt=tt+tn       Print ni & ": " & Format(tn,"00000.00000") & "s."    Next    Print "Average: " & tt / n & "s." End Sub

The line with k=Len(s)=0 varied and gave the following average timings over 10 tests:

Const s=""	k=Len(s)=0	7.532s
Const s=""	k=s<>""	58.938s
Const s="xxxxxxxxxx"	k=Len(s)=0	7.688s
Const s="xxxxxxxxxx"	k=s<>""	63.089s
Const s="xxxxxxxxxx"	k=s=""	65.770s

That means, even with small loops like 1 billion iterations, you get almost a minute faster results! Anyway, the number of iterations is not so important and you can't really judge on that, as someone might need even bigger iterations, but the fact that it's over 780% faster to use len(s) is important.

I don't think it's concidence that several people started to blog about LotusScript performance practices, just after I started to think about revising the LotusSphere 2007 LotusScript speed presentation, even before I posted anything on my blog. I think there is somekind of shared mind, which we can't explain scientifically yet.